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Can you explain the answer of this question below:The strength is the ability of a material to resist
- A:
deformation under stress
- B:
externally applied forces with breakdown or yielding
- C:
fracture due to high impact loads
- D:
none of these
The answer is b.
The strength is the ability of a material to resist
deformation under stress
externally applied forces with breakdown or yielding
fracture due to high impact loads
none of these
|
Disha Nambiar answered |
**The Strength of a Material**
The strength of a material refers to its ability to resist externally applied forces without breaking down or yielding. It is an important property that determines the structural integrity and reliability of engineering components. In this question, we are asked to identify the correct definition of strength from the given options.
**Understanding the Options**
Before discussing the correct answer, let's briefly understand the other options:
A: Deformation under Stress - Deformation refers to the change in shape or size of a material when subjected to an external force or stress. While strength certainly affects deformation, it does not fully define the concept of strength.
C: Fracture due to High Impact Loads - Fracture occurs when a material breaks apart due to the application of high impact loads. While strength does play a role in fracture resistance, it does not encompass the broader concept of strength.
D: None of These - This option suggests that none of the given options correctly define strength. However, since we are looking for the correct answer, we can eliminate this option.
**The Correct Answer - B: Externally Applied Forces with Breakdown or Yielding**
The correct answer to the question is option B: externally applied forces with breakdown or yielding. This option accurately describes the fundamental concept of strength. When a material is subjected to external forces such as tension, compression, or shear, it will either break down or yield, depending on its strength.
**Breakdown vs Yielding**
Breakdown refers to the point at which a material fails completely under the applied forces. It can occur suddenly and catastrophically, leading to complete structural failure. Yielding, on the other hand, refers to a gradual deformation or permanent change in shape that occurs when the material reaches its yield strength. Yielding is a reversible process, meaning that the material can return to its original shape once the applied forces are removed.
**Importance of Strength in Engineering**
The strength of a material is a crucial consideration in engineering design and structural analysis. It determines the maximum load a component can withstand without failure, ensuring the safety and reliability of structures. Engineers must carefully select materials with appropriate strength properties based on the specific application and expected loads. Additionally, strength analysis helps identify potential failure points and allows for the optimization of component designs to enhance performance and increase safety margins.
In conclusion, the strength of a material refers to its ability to resist externally applied forces without breaking down or yielding. It is a critical property that influences the structural integrity and reliability of engineering components.
The strength of a material refers to its ability to resist externally applied forces without breaking down or yielding. It is an important property that determines the structural integrity and reliability of engineering components. In this question, we are asked to identify the correct definition of strength from the given options.
**Understanding the Options**
Before discussing the correct answer, let's briefly understand the other options:
A: Deformation under Stress - Deformation refers to the change in shape or size of a material when subjected to an external force or stress. While strength certainly affects deformation, it does not fully define the concept of strength.
C: Fracture due to High Impact Loads - Fracture occurs when a material breaks apart due to the application of high impact loads. While strength does play a role in fracture resistance, it does not encompass the broader concept of strength.
D: None of These - This option suggests that none of the given options correctly define strength. However, since we are looking for the correct answer, we can eliminate this option.
**The Correct Answer - B: Externally Applied Forces with Breakdown or Yielding**
The correct answer to the question is option B: externally applied forces with breakdown or yielding. This option accurately describes the fundamental concept of strength. When a material is subjected to external forces such as tension, compression, or shear, it will either break down or yield, depending on its strength.
**Breakdown vs Yielding**
Breakdown refers to the point at which a material fails completely under the applied forces. It can occur suddenly and catastrophically, leading to complete structural failure. Yielding, on the other hand, refers to a gradual deformation or permanent change in shape that occurs when the material reaches its yield strength. Yielding is a reversible process, meaning that the material can return to its original shape once the applied forces are removed.
**Importance of Strength in Engineering**
The strength of a material is a crucial consideration in engineering design and structural analysis. It determines the maximum load a component can withstand without failure, ensuring the safety and reliability of structures. Engineers must carefully select materials with appropriate strength properties based on the specific application and expected loads. Additionally, strength analysis helps identify potential failure points and allows for the optimization of component designs to enhance performance and increase safety margins.
In conclusion, the strength of a material refers to its ability to resist externally applied forces without breaking down or yielding. It is a critical property that influences the structural integrity and reliability of engineering components.
Which of the following property is desirable in parts subjected to shock and impact loads ?- a)Strength
- b)Stiffness
- c)Brittleness
- d)Toughness
Correct answer is option 'D'. Can you explain this answer?
Which of the following property is desirable in parts subjected to shock and impact loads ?
a)
Strength
b)
Stiffness
c)
Brittleness
d)
Toughness
|
Baishali Bajaj answered |
In materials science and metallurgy, toughness is the ability of a material to absorb energy and plastically deform without fracturing. One definition of material toughness is the amount of energy per unit volume that a material can absorb before rupturing.
Iron ore is, usually, found in the form of- a)oxides
- b)carbonates
- c)sulphides
- d)all of these
Correct answer is option 'D'. Can you explain this answer?
Iron ore is, usually, found in the form of
a)
oxides
b)
carbonates
c)
sulphides
d)
all of these
|
Rahul Chatterjee answered |
Copper and silver are also found in the form of sulphide and oxide ores. Metals found in the middle of reactivity series, such as Zn, Fe, Pb, etc. are usually found in the form of oxides, sulphides or carbonates.
The following types of materials are usually the most ductile- a)face-centred cubic lattice
- b)body-centred cubic lattice
- c)hexagonal close-packed lattice
- d)all of the above
- e)none of the above
Correct answer is option 'A'. Can you explain this answer?
The following types of materials are usually the most ductile
a)
face-centred cubic lattice
b)
body-centred cubic lattice
c)
hexagonal close-packed lattice
d)
all of the above
e)
none of the above
|
Shivam Sharma answered |
The face centered cubic structure has atoms located at each of the corners and the centers of all the cubic faces (left image below). Additionally, each of its six face centered atoms is shared with an adjacent atom. Since 12 of its atoms are shared, it is said to have a coordination number of 12.
Cast iron is a ductile material- a)Right
- b)Wrong
- c)none of the above
- d)all the above
Correct answer is option 'B'. Can you explain this answer?
Cast iron is a ductile material
a)
Right
b)
Wrong
c)
none of the above
d)
all the above
|
Rajesh Raj answered |
Ductile materials has Tensile strength... Due to this reason Cast iron is not a Ductile material.
The cupola is used to manufacture- a)pig iron
- b)cast iron
- c)wrought iron
- d)steel
Correct answer is option 'B'. Can you explain this answer?
The cupola is used to manufacture
a)
pig iron
b)
cast iron
c)
wrought iron
d)
steel
|
Mrinalini Sen answered |
A cupola or cupola furnace is a melting device used in foundries that can be used to melt cast iron, Ni-resist iron and some bronzes. The cupola can be made almost any practical size.
Blast furnace is used to produce- a)pig iron
- b)cast iron
- c)wrought iron
- d)steel
Correct answer is option 'A'. Can you explain this answer?
Blast furnace is used to produce
a)
pig iron
b)
cast iron
c)
wrought iron
d)
steel
|
Tanvi Shah answered |
Blast furnaces are used to produce pig iron from iron ore for subsequent processing into steel, and they are also employed in processing lead, copper, and other metals. Rapid combustion is maintained by the current of air under pressure.
Railway rails are normally made of- a)mild steel
- b)alloy steel
- c)high carbon
- d)tungsten steel
- e)cast iron steel
Correct answer is option 'C'. Can you explain this answer?
Railway rails are normally made of
a)
mild steel
b)
alloy steel
c)
high carbon
d)
tungsten steel
e)
cast iron steel
|
|
Rajeev Sharma answered |
Modern track typically uses hot-rolled steel and corbon with a profile of an asymmetrical rounded I-beam. Unlike some other uses of iron and steel, railway rails are subject to very high stresses and have to be made of very high-quality steel alloy.
Which of the following constituents of steels is softest and least strong ?- a)austenite
- b)pearlite
- c)ferrite
- d)cementite
Correct answer is option 'C'. Can you explain this answer?
Which of the following constituents of steels is softest and least strong ?
a)
austenite
b)
pearlite
c)
ferrite
d)
cementite
|
|
Rahul Chatterjee answered |
Ferrite: It is a BCC iron phase with very limited solubility of carbon. The solubility of carbon in ferrite is 0.08% at 723degC. Ferrite does not harden when cooled rapidly. It is very soft and highly magnetic. At room temperature ferrite contains maximum 0.0025% C only.
Cyaniding is the process of- a)dipping steel in cyanide bath
- b)reacting steel surface with cyanide salts
- c)adding carbon and nitrogen by heat treatment of steel to increase its surface hardness
- d)obtaining cyanide salts
- e)making corrosion resistant steel
Correct answer is option 'C'. Can you explain this answer?
Cyaniding is the process of
a)
dipping steel in cyanide bath
b)
reacting steel surface with cyanide salts
c)
adding carbon and nitrogen by heat treatment of steel to increase its surface hardness
d)
obtaining cyanide salts
e)
making corrosion resistant steel
|
|
Shivam Sharma answered |
Liquid carburizing is a process used for case hardening steel or iron parts. The parts are held at a temperature above Ac1 in a molten salt that introduces carbon and nitrogen, or carbon alone, into the metal. Most liquid carburizing baths contain cyanide, which introduces both carbon and nitrogen into the case.
The property of a material which enables it to retain the deformation permanently, is called- a)brittleness
- b)ductility
- c)malleability
- d)plasticity
Correct answer is option 'D'. Can you explain this answer?
The property of a material which enables it to retain the deformation permanently, is called
a)
brittleness
b)
ductility
c)
malleability
d)
plasticity
|
Chandra Prakash Mishra answered |
The term retain means to save that condition as mention in the question.plasticity is quality that enable it to save the deformation of material means due to this property material doesnt get its original shape size...basically this is root property of material to deform
A steel containing 16 to 18% chromium and about 0.12% carbon is called- a)ferritic stainless steel
- b)austenitic stainless steel
- c)martensitic stainless steel
- d)nickel steel
Correct answer is option 'A'. Can you explain this answer?
A steel containing 16 to 18% chromium and about 0.12% carbon is called
a)
ferritic stainless steel
b)
austenitic stainless steel
c)
martensitic stainless steel
d)
nickel steel
|
Jhanvi Choudhary answered |
Ferritic Stainless Steel
Definition:
Ferritic stainless steel is a type of stainless steel that contains 16 to 18% chromium and about 0.12% carbon.
Composition:
Ferritic stainless steel typically contains the following elements:
- Chromium: 16-18%
- Carbon: 0.12% (maximum)
- Other elements: Silicon, Manganese, Phosphorus, Sulfur
Properties:
Ferritic stainless steel has the following properties:
- Magnetic
- Good corrosion resistance
- Good weldability
- Low thermal expansion coefficient
- Low thermal conductivity
- Low yield strength
- Low ductility
Applications:
Ferritic stainless steel is used in the following applications:
- Automotive exhaust systems
- Industrial equipment
- Kitchen appliances
- Heat exchangers
- Decorative trim
Conclusion:
Ferritic stainless steel is a type of stainless steel that contains 16 to 18% chromium and about 0.12% carbon. It has good corrosion resistance, weldability, and is used in various applications such as automotive exhaust systems, industrial equipment, and kitchen appliances.
Definition:
Ferritic stainless steel is a type of stainless steel that contains 16 to 18% chromium and about 0.12% carbon.
Composition:
Ferritic stainless steel typically contains the following elements:
- Chromium: 16-18%
- Carbon: 0.12% (maximum)
- Other elements: Silicon, Manganese, Phosphorus, Sulfur
Properties:
Ferritic stainless steel has the following properties:
- Magnetic
- Good corrosion resistance
- Good weldability
- Low thermal expansion coefficient
- Low thermal conductivity
- Low yield strength
- Low ductility
Applications:
Ferritic stainless steel is used in the following applications:
- Automotive exhaust systems
- Industrial equipment
- Kitchen appliances
- Heat exchangers
- Decorative trim
Conclusion:
Ferritic stainless steel is a type of stainless steel that contains 16 to 18% chromium and about 0.12% carbon. It has good corrosion resistance, weldability, and is used in various applications such as automotive exhaust systems, industrial equipment, and kitchen appliances.
Which of the following inpurity in cast iron makes it hard and brittle ?- a)Silicon
- b)Sulphur
- c)Manganese
- d)Phosphorus
Correct answer is option 'B'. Can you explain this answer?
Which of the following inpurity in cast iron makes it hard and brittle ?
a)
Silicon
b)
Sulphur
c)
Manganese
d)
Phosphorus
|
Ishaan Kulkarni answered |
Impurity in Cast Iron: Sulphur
Introduction:
Cast iron is a group of iron-carbon alloys with a carbon content greater than 2%. It is widely used in various industries due to its excellent castability, wear resistance, and high thermal conductivity. However, the properties of cast iron can be significantly influenced by the presence of impurities. One of the impurities that can have a detrimental effect on the mechanical properties of cast iron is sulphur.
Effects of Sulphur on Cast Iron:
Sulphur is generally considered as an undesirable impurity in cast iron due to its negative impact on the material's mechanical properties. The presence of sulphur in cast iron can lead to the following effects:
1. Hardness: Sulphur forms iron sulfide (FeS) in cast iron, which is a brittle compound. The presence of iron sulfide can increase the hardness of the material, making it more brittle.
2. Brittleness: The formation of iron sulfide in cast iron can cause the material to become brittle. Brittle materials are prone to fracture without undergoing significant deformation, which can be undesirable in many applications.
3. Reduced Ductility: Ductility refers to the ability of a material to deform under tensile stress without fracturing. The presence of sulphur can reduce the ductility of cast iron, making it more prone to brittle failure.
4. Reduced Toughness: Toughness is the ability of a material to absorb energy before fracture. Sulphur can reduce the toughness of cast iron by promoting the formation of brittle phases, leading to a decrease in the material's ability to withstand impact or sudden loads.
5. Decreased Machinability: Sulphur can also have a negative impact on the machinability of cast iron. The presence of sulphur can result in the formation of hard and abrasive particles, which can accelerate tool wear and increase machining difficulties.
Conclusion:
In conclusion, sulphur is an impurity in cast iron that can significantly affect its mechanical properties. The presence of sulphur can lead to increased hardness, brittleness, reduced ductility, decreased toughness, and decreased machinability. Therefore, it is important to control the sulphur content in cast iron to ensure desirable mechanical properties for different applications.
Introduction:
Cast iron is a group of iron-carbon alloys with a carbon content greater than 2%. It is widely used in various industries due to its excellent castability, wear resistance, and high thermal conductivity. However, the properties of cast iron can be significantly influenced by the presence of impurities. One of the impurities that can have a detrimental effect on the mechanical properties of cast iron is sulphur.
Effects of Sulphur on Cast Iron:
Sulphur is generally considered as an undesirable impurity in cast iron due to its negative impact on the material's mechanical properties. The presence of sulphur in cast iron can lead to the following effects:
1. Hardness: Sulphur forms iron sulfide (FeS) in cast iron, which is a brittle compound. The presence of iron sulfide can increase the hardness of the material, making it more brittle.
2. Brittleness: The formation of iron sulfide in cast iron can cause the material to become brittle. Brittle materials are prone to fracture without undergoing significant deformation, which can be undesirable in many applications.
3. Reduced Ductility: Ductility refers to the ability of a material to deform under tensile stress without fracturing. The presence of sulphur can reduce the ductility of cast iron, making it more prone to brittle failure.
4. Reduced Toughness: Toughness is the ability of a material to absorb energy before fracture. Sulphur can reduce the toughness of cast iron by promoting the formation of brittle phases, leading to a decrease in the material's ability to withstand impact or sudden loads.
5. Decreased Machinability: Sulphur can also have a negative impact on the machinability of cast iron. The presence of sulphur can result in the formation of hard and abrasive particles, which can accelerate tool wear and increase machining difficulties.
Conclusion:
In conclusion, sulphur is an impurity in cast iron that can significantly affect its mechanical properties. The presence of sulphur can lead to increased hardness, brittleness, reduced ductility, decreased toughness, and decreased machinability. Therefore, it is important to control the sulphur content in cast iron to ensure desirable mechanical properties for different applications.
The gray cast iron has ____- a)high melting point
- b)high thermal conductivity
- c)low compressive strength
- d)all of the above
Correct answer is option 'B'. Can you explain this answer?
The gray cast iron has ____
a)
high melting point
b)
high thermal conductivity
c)
low compressive strength
d)
all of the above
|
Sagarika Patel answered |
Gray iron, or grey cast iron, is a type of cast iron that has a graphitic microstructure. It is named after the gray color of the fracture it forms, which is due to the presence of graphite. It is the most common cast iron and the most widely used cast material based on weight.
The percentage of carbon in pig iron varies from- a)0.1 to 1.2%
- b)1.5 to 2.5%
- c)2.5 to 4%
- d)4 to 4.5%
- e)4.5 to 6.3%
Correct answer is option 'D'. Can you explain this answer?
The percentage of carbon in pig iron varies from
a)
0.1 to 1.2%
b)
1.5 to 2.5%
c)
2.5 to 4%
d)
4 to 4.5%
e)
4.5 to 6.3%
|
Partho Choudhary answered |
Pig iron contains at least 92% Fe and has a very high carbon content, typically 3.5 - 4.5%.
Carbon in iron is an example of- a)substitutional solution
- b)interstitial solid solution
- c)intermetallic compounds
- d)all of the above
- e)none of the above
Correct answer is option 'B'. Can you explain this answer?
Carbon in iron is an example of
a)
substitutional solution
b)
interstitial solid solution
c)
intermetallic compounds
d)
all of the above
e)
none of the above
|
Bhargavi Sarkar answered |
Carbon in iron is an example of interstitial solid solution.
Explanation:
- Interstitial solid solution occurs when atoms of a solute element fit into the interstices or gaps between the atoms of the solvent element in a solid solution.
- In the case of carbon in iron, carbon atoms are smaller than iron atoms. When carbon atoms are added to iron, they fit into the interstitial spaces between the iron atoms.
- The addition of carbon to iron forms a solid solution known as steel. Steel is a strong and versatile material widely used in various industries.
- The carbon atoms in the steel lattice significantly influence its properties, such as hardness, strength, and ductility.
- The amount of carbon in steel determines its carbon content and affects its properties. Low carbon steel contains a small amount of carbon (up to 0.25%), while high carbon steel contains a higher amount of carbon (up to 2%).
- The presence of carbon in steel also affects its microstructure. For example, high carbon steel tends to have a harder and more brittle microstructure compared to low carbon steel.
- Interstitial solid solutions can also occur in other metal systems, where small atoms of one element occupy the interstitial spaces of a metal lattice. This can influence the properties of the resulting solid solution.
In summary, carbon in iron is an example of an interstitial solid solution, where carbon atoms occupy the interstitial spaces between iron atoms in the lattice structure of steel.
Explanation:
- Interstitial solid solution occurs when atoms of a solute element fit into the interstices or gaps between the atoms of the solvent element in a solid solution.
- In the case of carbon in iron, carbon atoms are smaller than iron atoms. When carbon atoms are added to iron, they fit into the interstitial spaces between the iron atoms.
- The addition of carbon to iron forms a solid solution known as steel. Steel is a strong and versatile material widely used in various industries.
- The carbon atoms in the steel lattice significantly influence its properties, such as hardness, strength, and ductility.
- The amount of carbon in steel determines its carbon content and affects its properties. Low carbon steel contains a small amount of carbon (up to 0.25%), while high carbon steel contains a higher amount of carbon (up to 2%).
- The presence of carbon in steel also affects its microstructure. For example, high carbon steel tends to have a harder and more brittle microstructure compared to low carbon steel.
- Interstitial solid solutions can also occur in other metal systems, where small atoms of one element occupy the interstitial spaces of a metal lattice. This can influence the properties of the resulting solid solution.
In summary, carbon in iron is an example of an interstitial solid solution, where carbon atoms occupy the interstitial spaces between iron atoms in the lattice structure of steel.
Solder is an alloy consisting of- a)tin, antimony, copper
- b)tin and copper
- c)tin and Aluminium
- d)lead and zinc
- e)lead and copper
Correct answer is option 'B'. Can you explain this answer?
Solder is an alloy consisting of
a)
tin, antimony, copper
b)
tin and copper
c)
tin and Aluminium
d)
lead and zinc
e)
lead and copper
|
Dipika Bose answered |
Actuallly there were two types of solder tin-lead alloy and tin copper alloy.Due restrictions in several countries only tin-copper solder is in use now.
Duplex process of steel making is a combination of- a)basic bessemer and acid open hearth processes
- b)acid bessemer and basic open hearth processes
- c)acid bessemer and acid open hearth processes
- d)basic bessemer and basic open hearth processes
Correct answer is option 'B'. Can you explain this answer?
Duplex process of steel making is a combination of
a)
basic bessemer and acid open hearth processes
b)
acid bessemer and basic open hearth processes
c)
acid bessemer and acid open hearth processes
d)
basic bessemer and basic open hearth processes
|
Anirban Khanna answered |
This is merely a combination of the Bessemer and open-hearth processes.
Pig metal is blown in an acid Bessemer converter until silicon, manganese, and part or all of the carbon are removed. It is then practically a molten steel high in phosphorus. From the converter it is conveyed to the basic open-hearth furnace for refining, for removal of the phosphorus, and for re-carburization.
The advantage claimed for this process is that it saves time, brings less wear and tear on the open-hearth furnace (which is the expensive furnace in steel making), and gives a better product than by the open-hearth process alone. It combines the acid process of the converter with the basic process of the furnace.
In grey cast iron, carbon is present in the form of
- a)cementite
- b)free carbon
- c)flakes
- d)spheroids
- e)nodular aggregates of graphite
Correct answer is option 'C'. Can you explain this answer?
In grey cast iron, carbon is present in the form of
a)
cementite
b)
free carbon
c)
flakes
d)
spheroids
e)
nodular aggregates of graphite
|
|
Akanksha Tiwari answered |
Grey Cast Iron and the presence of Carbon
Grey Cast Iron
Grey cast iron is a type of cast iron that contains graphite flakes in its microstructure. This gives it its characteristic grey color. Grey cast iron is relatively brittle and has low tensile strength, but it is also easy to cast and has good machinability.
Presence of Carbon in Grey Cast Iron
Carbon is a key component of grey cast iron. It is present in the form of flakes, which are formed during the solidification process. The carbon content of grey cast iron typically ranges from 2.5 to 4.0 percent.
Flakes
The carbon in grey cast iron is present in the form of flakes, which are also known as graphite. These flakes are the result of the way in which the carbon solidifies during the casting process. As the iron cools and solidifies, the carbon separates out and forms flakes or plates within the iron matrix. These flakes give the iron its characteristic grey color and also contribute to its brittleness.
Conclusion
In conclusion, carbon is present in grey cast iron in the form of flakes. These flakes are formed during the solidification process and give the iron its characteristic grey color. While grey cast iron is relatively brittle and has low tensile strength, it is also easy to cast and has good machinability.
Grey Cast Iron
Grey cast iron is a type of cast iron that contains graphite flakes in its microstructure. This gives it its characteristic grey color. Grey cast iron is relatively brittle and has low tensile strength, but it is also easy to cast and has good machinability.
Presence of Carbon in Grey Cast Iron
Carbon is a key component of grey cast iron. It is present in the form of flakes, which are formed during the solidification process. The carbon content of grey cast iron typically ranges from 2.5 to 4.0 percent.
Flakes
The carbon in grey cast iron is present in the form of flakes, which are also known as graphite. These flakes are the result of the way in which the carbon solidifies during the casting process. As the iron cools and solidifies, the carbon separates out and forms flakes or plates within the iron matrix. These flakes give the iron its characteristic grey color and also contribute to its brittleness.
Conclusion
In conclusion, carbon is present in grey cast iron in the form of flakes. These flakes are formed during the solidification process and give the iron its characteristic grey color. While grey cast iron is relatively brittle and has low tensile strength, it is also easy to cast and has good machinability.
Which of the following parameters is/are false for steel?- a) High carbon content
- b)High melting point
- c)Low damping capacity
- d)None of the above
- e)none of the above
Correct answer is option 'A'. Can you explain this answer?
Which of the following parameters is/are false for steel?
a)
High carbon content
b)
High melting point
c)
Low damping capacity
d)
None of the above
e)
none of the above
|
Pritam Jain answered |
False Parameter for Steel
High Carbon Content is a false parameter for steel. Steel is an alloy of iron and carbon, where the carbon content varies from 0.2% to 2.1% by weight. However, high carbon content is not desired in steel as it reduces the ductility and toughness of the material. The ideal carbon content in steel depends on the application and the desired properties.
True Parameters for Steel
High Melting Point: Steel has a high melting point, which makes it suitable for applications where high temperatures are involved. The melting point of steel varies depending on the composition and ranges from 1370°C to 1530°C.
High Strength: Steel is known for its high strength, which makes it suitable for structural applications. The strength of steel depends on the composition and the heat treatment.
Good Ductility: Steel has good ductility, which means it can be easily deformed without breaking. This property makes it suitable for applications where the material needs to be bent or formed.
Good Toughness: Steel has good toughness, which means it can absorb energy without breaking. This property makes it suitable for applications where the material needs to withstand impact or shock.
Good Corrosion Resistance: Steel can be made corrosion-resistant by adding alloying elements such as chromium, nickel, and molybdenum. This property makes it suitable for applications where the material is exposed to harsh environments.
Conclusion
Steel is a versatile material that can be tailored to meet different applications by varying its composition and heat treatment. While high carbon content is not desirable in steel, it has several other properties such as high melting point, strength, ductility, toughness, and corrosion resistance that make it suitable for a wide range of applications.
High Carbon Content is a false parameter for steel. Steel is an alloy of iron and carbon, where the carbon content varies from 0.2% to 2.1% by weight. However, high carbon content is not desired in steel as it reduces the ductility and toughness of the material. The ideal carbon content in steel depends on the application and the desired properties.
True Parameters for Steel
High Melting Point: Steel has a high melting point, which makes it suitable for applications where high temperatures are involved. The melting point of steel varies depending on the composition and ranges from 1370°C to 1530°C.
High Strength: Steel is known for its high strength, which makes it suitable for structural applications. The strength of steel depends on the composition and the heat treatment.
Good Ductility: Steel has good ductility, which means it can be easily deformed without breaking. This property makes it suitable for applications where the material needs to be bent or formed.
Good Toughness: Steel has good toughness, which means it can absorb energy without breaking. This property makes it suitable for applications where the material needs to withstand impact or shock.
Good Corrosion Resistance: Steel can be made corrosion-resistant by adding alloying elements such as chromium, nickel, and molybdenum. This property makes it suitable for applications where the material is exposed to harsh environments.
Conclusion
Steel is a versatile material that can be tailored to meet different applications by varying its composition and heat treatment. While high carbon content is not desirable in steel, it has several other properties such as high melting point, strength, ductility, toughness, and corrosion resistance that make it suitable for a wide range of applications.
Delta iron occurs at temperature of- a)room temperature
- b)above melting point
- c)between 910ºC and 1539ºC
- d)between 910ºC and 1400ºC
Correct answer is option 'C'. Can you explain this answer?
Delta iron occurs at temperature of
a)
room temperature
b)
above melting point
c)
between 910ºC and 1539ºC
d)
between 910ºC and 1400ºC
|
Kritika Shah answered |
Delta iron, also known as δ-iron or ferrite, is a solid phase of iron that exists at elevated temperatures. It undergoes a phase transformation from austenite to delta ferrite during cooling. The correct answer to the question is option 'C', which states that delta iron occurs between 910°C and 1539°C. Let's understand why this is the correct answer.
Delta iron formation temperature:
Delta iron forms when the temperature of iron is in the range of 910°C to 1539°C. This temperature range is above the melting point of iron, which is around 1538°C. At temperatures above the melting point, iron is in the liquid phase. However, during the cooling process, as the temperature decreases, the liquid iron undergoes a phase transformation and solidifies into delta iron.
Phase transformation from austenite to delta ferrite:
At high temperatures, iron exists in the austenite phase, which has a face-centered cubic (fcc) crystal structure. As the temperature decreases, the crystal structure of iron changes. At temperatures above 910°C, the austenite phase transforms into delta ferrite, which has a body-centered cubic (bcc) crystal structure. This transformation is known as the ferrite transformation.
Key points:
- Delta iron is a solid phase of iron.
- It forms between 910°C and 1539°C.
- It occurs during the cooling process of liquid iron.
- Delta iron has a bcc crystal structure.
- It is formed from the transformation of austenite to delta ferrite.
In conclusion, delta iron occurs at temperatures between 910°C and 1539°C, which is above the melting point of iron. It forms during the cooling process as the austenite phase transforms into delta ferrite.
Delta iron formation temperature:
Delta iron forms when the temperature of iron is in the range of 910°C to 1539°C. This temperature range is above the melting point of iron, which is around 1538°C. At temperatures above the melting point, iron is in the liquid phase. However, during the cooling process, as the temperature decreases, the liquid iron undergoes a phase transformation and solidifies into delta iron.
Phase transformation from austenite to delta ferrite:
At high temperatures, iron exists in the austenite phase, which has a face-centered cubic (fcc) crystal structure. As the temperature decreases, the crystal structure of iron changes. At temperatures above 910°C, the austenite phase transforms into delta ferrite, which has a body-centered cubic (bcc) crystal structure. This transformation is known as the ferrite transformation.
Key points:
- Delta iron is a solid phase of iron.
- It forms between 910°C and 1539°C.
- It occurs during the cooling process of liquid iron.
- Delta iron has a bcc crystal structure.
- It is formed from the transformation of austenite to delta ferrite.
In conclusion, delta iron occurs at temperatures between 910°C and 1539°C, which is above the melting point of iron. It forms during the cooling process as the austenite phase transforms into delta ferrite.
Which of the following is a mesomorphous material ?- a)Mica
- b)Silver
- c)Lead
- d)Brass
Correct answer is option 'A'. Can you explain this answer?
Which of the following is a mesomorphous material ?
a)
Mica
b)
Silver
c)
Lead
d)
Brass
|
Ameya Kaur answered |
Mesomorphous Materials
Mesomorphous materials are the materials that exhibit a transition between crystalline and amorphous phases. They possess a unique combination of properties that make them useful in various applications, including electronics, optics, and energy storage.
Mica
Mica is a mesomorphous material that exhibits a transition between a crystalline and amorphous phase. It is a mineral that occurs naturally in many rocks and is commonly used in electrical insulation due to its high dielectric strength.
Silver
Silver is a metallic element that is not a mesomorphous material. It has a well-defined crystal structure and does not exhibit a transition between a crystalline and amorphous phase.
Lead
Lead is a metallic element that is not a mesomorphous material. It has a well-defined crystal structure and does not exhibit a transition between a crystalline and amorphous phase.
Brass
Brass is a metal alloy that is not a mesomorphous material. It is composed of copper and zinc and has a well-defined crystal structure. It does not exhibit a transition between a crystalline and amorphous phase.
Conclusion
Mica is a mesomorphous material that exhibits a transition between a crystalline and amorphous phase. It possesses unique properties that make it useful in various applications. On the other hand, silver, lead, and brass are not mesomorphous materials as they have well-defined crystal structures and do not exhibit a transition between a crystalline and amorphous phase.
Mesomorphous materials are the materials that exhibit a transition between crystalline and amorphous phases. They possess a unique combination of properties that make them useful in various applications, including electronics, optics, and energy storage.
Mica
Mica is a mesomorphous material that exhibits a transition between a crystalline and amorphous phase. It is a mineral that occurs naturally in many rocks and is commonly used in electrical insulation due to its high dielectric strength.
Silver
Silver is a metallic element that is not a mesomorphous material. It has a well-defined crystal structure and does not exhibit a transition between a crystalline and amorphous phase.
Lead
Lead is a metallic element that is not a mesomorphous material. It has a well-defined crystal structure and does not exhibit a transition between a crystalline and amorphous phase.
Brass
Brass is a metal alloy that is not a mesomorphous material. It is composed of copper and zinc and has a well-defined crystal structure. It does not exhibit a transition between a crystalline and amorphous phase.
Conclusion
Mica is a mesomorphous material that exhibits a transition between a crystalline and amorphous phase. It possesses unique properties that make it useful in various applications. On the other hand, silver, lead, and brass are not mesomorphous materials as they have well-defined crystal structures and do not exhibit a transition between a crystalline and amorphous phase.
Smelting is the process of- a)removing the impurities like clay, sand etc. from the iron ore by washing with water
- b)expelling moisture, carbon dioxide, sulphur and arsenic from the iron ore by heating in shallow kilns
- c)reducing the ore with carbon in the presence of a flux
- d)all of the above
Correct answer is option 'C'. Can you explain this answer?
Smelting is the process of
a)
removing the impurities like clay, sand etc. from the iron ore by washing with water
b)
expelling moisture, carbon dioxide, sulphur and arsenic from the iron ore by heating in shallow kilns
c)
reducing the ore with carbon in the presence of a flux
d)
all of the above
|
|
Baishali Bajaj answered |
Process- Smelting involves more than just melting the metal out of its ore. Most ores are the chemical compound of the metal and other elements, such as oxygen (as an oxide), sulfur (as a sulfide), or carbon and oxygen together (as a carbonate).
Sulphur in pig iron tends to make it- a)hard
- b)soft
- c)ductile
- d)tough
- e)malleable
Correct answer is option 'E'. Can you explain this answer?
Sulphur in pig iron tends to make it
a)
hard
b)
soft
c)
ductile
d)
tough
e)
malleable
|
Anjali Kapoor answered |
As sulfur in Pig Iron make the cast iron manufacturing unsound and not pure because sulfur works as a impurities in Pig iron. The sulfur in cast iron create impurities and the effects of the sulfur present in the pig iron effects there products Longevity.
The quantity of sulphur present in ores of iron varies from 0.4% to 1.0%. The combination with sulphur in iron and forming MnS. MnS formed thus combines with CaO and is removed. In this way the percentage of sulphur in iron is reduced. The reaction of sulphur with manganese is as follows:
FeS + Mn → Fe + MnS
MnS + CaO → MnO + CaS (Slag)
MnO + C → Mn + CO
It may be noted that FeS has a low melting point and it forms between the grains that make up the alloy. Iron sulphide being very brittle, whole alloy becomes brittle.
Presence of sulfur tends to make iron hard and produces unsound castings. Wrought iron and steel produced from iron containing sulfur makes wrought iron and steel to be brittle when heated.
The iron foundry in India produced many products using cast iron that is cast iron bollards , rectangular manhole cover, Automotive casting and many more . Crescent Foundry is the top best iron foundry in kolkata which uses the latest techniques to design products and manufacturing.
The crystal of alpha iron is
- a)body centred cubic
- b)face centred cubic
- c)hexagonal close packed
- d)cubic structure
- e)orthorhombic crysta
Correct answer is option 'A'. Can you explain this answer?
The crystal of alpha iron is
a)
body centred cubic
b)
face centred cubic
c)
hexagonal close packed
d)
cubic structure
e)
orthorhombic crysta
|
|
Anshul Sharma answered |
The crystal structure of a material refers to the arrangement of atoms or ions in the solid state. In the case of alpha iron, the correct crystal structure is body-centered cubic (BCC). Let's understand why this is the correct answer.
Understanding Crystal Structures:
- There are various types of crystal structures, including body-centered cubic (BCC), face-centered cubic (FCC), hexagonal close packed (HCP), and others.
- Each crystal structure has a distinct arrangement of atoms or ions, which affects the material's properties and behavior.
Alpha Iron's Crystal Structure:
- Alpha iron is a form of iron that is stable below 912°C. It has a BCC crystal structure.
- In a BCC structure, the iron atoms are arranged in a repeating pattern where each iron atom is surrounded by eight neighboring atoms.
- The lattice structure of BCC iron consists of a cube with an atom at each corner and one atom in the center of the cube.
- The BCC structure results in a relatively open and less dense arrangement of atoms compared to other structures.
Reasons for Alpha Iron having a BCC Structure:
1. Stability: At temperatures below 912°C, alpha iron is the stable phase of iron. The BCC crystal structure allows the atoms to arrange themselves in a stable and energetically favorable manner.
2. Allotropy: Iron exhibits allotropy, meaning it can exist in different crystal structures at different temperatures. Alpha iron is one of the allotropes with a BCC structure.
3. Phase Transformation: When iron is heated above 912°C, it undergoes a phase transformation to a different crystal structure, known as gamma iron, which has an FCC (face-centered cubic) structure. This further confirms that alpha iron has a BCC structure at lower temperatures.
Conclusion:
In summary, the crystal structure of alpha iron is body-centered cubic (BCC). This structure is characterized by a cube-shaped lattice with iron atoms located at the corners and in the center of the cube. Understanding the crystal structure is crucial for understanding the properties and behavior of materials in various applications.
Understanding Crystal Structures:
- There are various types of crystal structures, including body-centered cubic (BCC), face-centered cubic (FCC), hexagonal close packed (HCP), and others.
- Each crystal structure has a distinct arrangement of atoms or ions, which affects the material's properties and behavior.
Alpha Iron's Crystal Structure:
- Alpha iron is a form of iron that is stable below 912°C. It has a BCC crystal structure.
- In a BCC structure, the iron atoms are arranged in a repeating pattern where each iron atom is surrounded by eight neighboring atoms.
- The lattice structure of BCC iron consists of a cube with an atom at each corner and one atom in the center of the cube.
- The BCC structure results in a relatively open and less dense arrangement of atoms compared to other structures.
Reasons for Alpha Iron having a BCC Structure:
1. Stability: At temperatures below 912°C, alpha iron is the stable phase of iron. The BCC crystal structure allows the atoms to arrange themselves in a stable and energetically favorable manner.
2. Allotropy: Iron exhibits allotropy, meaning it can exist in different crystal structures at different temperatures. Alpha iron is one of the allotropes with a BCC structure.
3. Phase Transformation: When iron is heated above 912°C, it undergoes a phase transformation to a different crystal structure, known as gamma iron, which has an FCC (face-centered cubic) structure. This further confirms that alpha iron has a BCC structure at lower temperatures.
Conclusion:
In summary, the crystal structure of alpha iron is body-centered cubic (BCC). This structure is characterized by a cube-shaped lattice with iron atoms located at the corners and in the center of the cube. Understanding the crystal structure is crucial for understanding the properties and behavior of materials in various applications.
18/8 stainless steel consists of- a)18% nickel and 8% chromium
- b)18% chromium and 8% nickel
- c)18% nickel and 18% chromium
- d)8% nickel and 8% chromium
Correct answer is option 'B'. Can you explain this answer?
18/8 stainless steel consists of
a)
18% nickel and 8% chromium
b)
18% chromium and 8% nickel
c)
18% nickel and 18% chromium
d)
8% nickel and 8% chromium
|
Asha Basu answered |
Composition of 18/8 Stainless Steel
- 18% Chromium and 8% Nickel: The 18/8 stainless steel composition refers to the percentages of chromium and nickel present in the alloy.
- Chromium: Chromium is a key element in stainless steel as it helps in giving the material its corrosion-resistant properties. It forms a thin oxide layer on the surface of the steel, which prevents rust and corrosion.
- Nickel: Nickel is another important element in stainless steel that enhances its resistance to corrosion and adds to its durability. It also helps in maintaining the luster and finish of the steel.
- Importance of Proper Composition: The specific ratio of 18% chromium and 8% nickel in 18/8 stainless steel provides a good balance of corrosion resistance, strength, and formability. This composition makes it suitable for a wide range of applications, from kitchen utensils to industrial equipment.
- Common Uses: 18/8 stainless steel is commonly used in household items like cookware, cutlery, and appliances, as well as in the food processing and pharmaceutical industries where hygiene and corrosion resistance are crucial.
- 18% Chromium and 8% Nickel: The 18/8 stainless steel composition refers to the percentages of chromium and nickel present in the alloy.
- Chromium: Chromium is a key element in stainless steel as it helps in giving the material its corrosion-resistant properties. It forms a thin oxide layer on the surface of the steel, which prevents rust and corrosion.
- Nickel: Nickel is another important element in stainless steel that enhances its resistance to corrosion and adds to its durability. It also helps in maintaining the luster and finish of the steel.
- Importance of Proper Composition: The specific ratio of 18% chromium and 8% nickel in 18/8 stainless steel provides a good balance of corrosion resistance, strength, and formability. This composition makes it suitable for a wide range of applications, from kitchen utensils to industrial equipment.
- Common Uses: 18/8 stainless steel is commonly used in household items like cookware, cutlery, and appliances, as well as in the food processing and pharmaceutical industries where hygiene and corrosion resistance are crucial.
Cast iron is manufactured in- a)blast furnace
- b)cupola
- c)open hearth furnace
- d)bessemer converter
Correct answer is option 'B'. Can you explain this answer?
Cast iron is manufactured in
a)
blast furnace
b)
cupola
c)
open hearth furnace
d)
bessemer converter
|
Swara Dasgupta answered |
Cast iron is sometimes melted in a special type of blast furnace known as a cupola, but in modern applications, it is more often melted in electric induction furnaces or electric arc furnaces. After melting is complete, the molten cast iron is poured into a holding furnace or ladle.
An example of amorphous materials is- a)zinc
- b)lead
- c)silver
- d)glass
- e)brass
Correct answer is option 'D'. Can you explain this answer?
An example of amorphous materials is
a)
zinc
b)
lead
c)
silver
d)
glass
e)
brass
|
|
Pankaj Joshi answered |
Amorphous Materials Example: Glass
Glass is a widely known example of an amorphous material. Unlike crystalline materials, amorphous materials do not have a regular, repeating atomic structure. Instead, their atoms are arranged randomly, leading to a lack of long-range order.
Characteristics of Amorphous Materials:
- Lack of long-range order in atomic arrangement
- Absence of definite melting point
- Can be formed by rapid cooling of a liquid
Properties of Glass:
- Transparency or translucency
- Brittle nature
- High resistance to chemical corrosion
Applications of Glass:
- Windows and glass panes
- Glass containers for storing liquids
- Optical lenses and fibers
In conclusion, glass serves as a prime example of amorphous materials due to its random atomic structure and unique properties. Its widespread applications in various industries highlight the importance and versatility of amorphous materials in our daily lives.
Glass is a widely known example of an amorphous material. Unlike crystalline materials, amorphous materials do not have a regular, repeating atomic structure. Instead, their atoms are arranged randomly, leading to a lack of long-range order.
Characteristics of Amorphous Materials:
- Lack of long-range order in atomic arrangement
- Absence of definite melting point
- Can be formed by rapid cooling of a liquid
Properties of Glass:
- Transparency or translucency
- Brittle nature
- High resistance to chemical corrosion
Applications of Glass:
- Windows and glass panes
- Glass containers for storing liquids
- Optical lenses and fibers
In conclusion, glass serves as a prime example of amorphous materials due to its random atomic structure and unique properties. Its widespread applications in various industries highlight the importance and versatility of amorphous materials in our daily lives.
The fuel used in a blast furnace is- a)coal
- b)coke
- c)wood
- d)producer gas
Correct answer is option 'B'. Can you explain this answer?
The fuel used in a blast furnace is
a)
coal
b)
coke
c)
wood
d)
producer gas
|
|
Niharika Iyer answered |
The fuel used in a blast furnace is coke.
Explanation:
A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, such as iron and steel. It is a large structure, typically cylindrical, where iron ore, coke, and limestone are fed into the top, while hot air is blown into the bottom. The intense heat generated causes a chemical reaction, resulting in the reduction of iron ore to iron.
1. Coke:
- Coke is the primary fuel used in a blast furnace.
- It is a solid carbonaceous material derived from coal.
- It is produced by heating coal in the absence of air to remove volatile compounds and moisture, leaving behind a carbon-rich material.
- Coke has a high carbon content, low impurities, and a high calorific value, making it an ideal fuel for the high-temperature smelting process in a blast furnace.
2. Advantages of Coke:
- High Carbon Content: Coke has a carbon content of around 90%, which provides a high heat value during combustion.
- Low Volatile Matter: Coke has a low volatile matter content, which reduces the amount of gas produced during combustion.
- High Calorific Value: The high carbon content and low impurities in coke result in a high calorific value, providing a significant amount of heat energy.
- Chemical Stability: Coke is chemically stable and does not react with the iron ore or other materials in the blast furnace, ensuring efficient smelting.
3. Other Fuels:
- Coal: Coal can be used as a fuel in a blast furnace, but it needs to be processed into coke before being used.
- Wood: Wood is not suitable as a fuel in a blast furnace due to its low carbon content and high moisture content.
- Producer Gas: Producer gas is a mixture of carbon monoxide, hydrogen, and other gases produced by the gasification of coal or biomass. While it can be used as a fuel, it is not commonly used in blast furnaces.
In summary, coke is the fuel of choice in a blast furnace due to its high carbon content, low impurities, and high calorific value. It provides the necessary heat energy for the smelting process and ensures efficient reduction of iron ore to iron.
Explanation:
A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, such as iron and steel. It is a large structure, typically cylindrical, where iron ore, coke, and limestone are fed into the top, while hot air is blown into the bottom. The intense heat generated causes a chemical reaction, resulting in the reduction of iron ore to iron.
1. Coke:
- Coke is the primary fuel used in a blast furnace.
- It is a solid carbonaceous material derived from coal.
- It is produced by heating coal in the absence of air to remove volatile compounds and moisture, leaving behind a carbon-rich material.
- Coke has a high carbon content, low impurities, and a high calorific value, making it an ideal fuel for the high-temperature smelting process in a blast furnace.
2. Advantages of Coke:
- High Carbon Content: Coke has a carbon content of around 90%, which provides a high heat value during combustion.
- Low Volatile Matter: Coke has a low volatile matter content, which reduces the amount of gas produced during combustion.
- High Calorific Value: The high carbon content and low impurities in coke result in a high calorific value, providing a significant amount of heat energy.
- Chemical Stability: Coke is chemically stable and does not react with the iron ore or other materials in the blast furnace, ensuring efficient smelting.
3. Other Fuels:
- Coal: Coal can be used as a fuel in a blast furnace, but it needs to be processed into coke before being used.
- Wood: Wood is not suitable as a fuel in a blast furnace due to its low carbon content and high moisture content.
- Producer Gas: Producer gas is a mixture of carbon monoxide, hydrogen, and other gases produced by the gasification of coal or biomass. While it can be used as a fuel, it is not commonly used in blast furnaces.
In summary, coke is the fuel of choice in a blast furnace due to its high carbon content, low impurities, and high calorific value. It provides the necessary heat energy for the smelting process and ensures efficient reduction of iron ore to iron.
Iron is- a)paramagnetic
- b)ferromagnetic
- c)ferroelectric
- d)dielectric
- e)none of the above
Correct answer is option 'B'. Can you explain this answer?
Iron is
a)
paramagnetic
b)
ferromagnetic
c)
ferroelectric
d)
dielectric
e)
none of the above
|
|
Anshul Basu answered |
Introduction:
Iron is a chemical element with the symbol Fe and atomic number 26. It is a common metal that is widely used in various industries due to its desirable properties. In terms of its magnetic behavior, iron is classified as ferromagnetic.
Ferromagnetic Behavior:
Ferromagnetism is a property exhibited by certain materials, including iron, where they can become strongly magnetized in the presence of an external magnetic field. This behavior arises due to the alignment of magnetic moments within the material. In the case of iron, its atomic structure allows for the alignment of magnetic moments to occur spontaneously, resulting in a strong magnetic response.
Paramagnetic vs. Ferromagnetic:
While both paramagnetic and ferromagnetic materials exhibit a weak attraction to an external magnetic field, there is a significant difference between the two:
Paramagnetic Materials:
- Paramagnetic materials have unpaired electrons, which give rise to weak magnetic moments.
- In the absence of an external magnetic field, the magnetic moments of paramagnetic materials are randomly oriented.
- When exposed to an external magnetic field, the magnetic moments align with the field but do not remain aligned when the field is removed.
Ferromagnetic Materials:
- Ferromagnetic materials also have unpaired electrons, but their atomic structure allows for the spontaneous alignment of magnetic moments.
- In the absence of an external magnetic field, the magnetic moments in ferromagnetic materials are already strongly aligned.
- When exposed to an external magnetic field, the alignment of magnetic moments in ferromagnetic materials is further enhanced, resulting in a stronger magnetic response.
- This alignment persists even after the external field is removed, making ferromagnetic materials capable of retaining a permanent magnetization.
Iron as Ferromagnetic:
Iron possesses a crystalline structure, which enables the spontaneous alignment of magnetic moments and the generation of a strong magnetic field. This property makes iron highly useful in applications such as electromagnets, transformers, magnetic storage devices, and various other industrial and technological applications.
Conclusion:
In summary, iron is classified as a ferromagnetic material due to its ability to spontaneously align magnetic moments and exhibit a strong magnetic response. This property sets it apart from paramagnetic materials, which exhibit a weaker and non-permanent magnetic behavior.
Iron is a chemical element with the symbol Fe and atomic number 26. It is a common metal that is widely used in various industries due to its desirable properties. In terms of its magnetic behavior, iron is classified as ferromagnetic.
Ferromagnetic Behavior:
Ferromagnetism is a property exhibited by certain materials, including iron, where they can become strongly magnetized in the presence of an external magnetic field. This behavior arises due to the alignment of magnetic moments within the material. In the case of iron, its atomic structure allows for the alignment of magnetic moments to occur spontaneously, resulting in a strong magnetic response.
Paramagnetic vs. Ferromagnetic:
While both paramagnetic and ferromagnetic materials exhibit a weak attraction to an external magnetic field, there is a significant difference between the two:
Paramagnetic Materials:
- Paramagnetic materials have unpaired electrons, which give rise to weak magnetic moments.
- In the absence of an external magnetic field, the magnetic moments of paramagnetic materials are randomly oriented.
- When exposed to an external magnetic field, the magnetic moments align with the field but do not remain aligned when the field is removed.
Ferromagnetic Materials:
- Ferromagnetic materials also have unpaired electrons, but their atomic structure allows for the spontaneous alignment of magnetic moments.
- In the absence of an external magnetic field, the magnetic moments in ferromagnetic materials are already strongly aligned.
- When exposed to an external magnetic field, the alignment of magnetic moments in ferromagnetic materials is further enhanced, resulting in a stronger magnetic response.
- This alignment persists even after the external field is removed, making ferromagnetic materials capable of retaining a permanent magnetization.
Iron as Ferromagnetic:
Iron possesses a crystalline structure, which enables the spontaneous alignment of magnetic moments and the generation of a strong magnetic field. This property makes iron highly useful in applications such as electromagnets, transformers, magnetic storage devices, and various other industrial and technological applications.
Conclusion:
In summary, iron is classified as a ferromagnetic material due to its ability to spontaneously align magnetic moments and exhibit a strong magnetic response. This property sets it apart from paramagnetic materials, which exhibit a weaker and non-permanent magnetic behavior.
Eutectoid steel contains following percentage of carbon- a)0.02%
- b)0.3%
- c)0.63%
- d)0.8%
- e)1.2%
Correct answer is option 'D'. Can you explain this answer?
Eutectoid steel contains following percentage of carbon
a)
0.02%
b)
0.3%
c)
0.63%
d)
0.8%
e)
1.2%
|
|
Athira Pillai answered |
Introduction:
Eutectoid steel is a type of carbon steel that undergoes a transformation known as eutectoid reaction. This reaction occurs at a specific temperature and results in the formation of a microstructure called pearlite. The percentage of carbon present in eutectoid steel is crucial in determining its properties and behavior.
Explanation:
To answer the given question, we need to understand the composition of eutectoid steel and its carbon percentage.
Eutectoid Reaction:
The eutectoid reaction occurs in iron-carbon alloys, specifically at a temperature of approximately 727°C (1341°F). At this temperature, the steel undergoes a phase change from austenite to pearlite. During this reaction, the carbon molecules redistribute and form layers of cementite within the ferrite matrix.
Carbon Percentage in Eutectoid Steel:
The composition of eutectoid steel is such that it contains exactly 0.76% carbon. This specific carbon percentage is critical because it allows the eutectoid reaction to occur at the eutectoid temperature.
Options:
a) 0.02% - This carbon percentage is significantly lower than the required 0.76% for eutectoid steel.
b) 0.3% - This carbon percentage is also lower than the required 0.76% for eutectoid steel.
c) 0.63% - This carbon percentage is still lower than the required 0.76% for eutectoid steel.
d) 0.8% - This carbon percentage is slightly higher than the required 0.76% for eutectoid steel. It is the correct answer.
e) 1.2% - This carbon percentage is higher than the required 0.76% for eutectoid steel.
Conclusion:
The correct answer for the percentage of carbon in eutectoid steel is option 'D' - 0.8%. This carbon percentage allows the eutectoid reaction to occur at the eutectoid temperature, resulting in the formation of pearlite microstructure.
Eutectoid steel is a type of carbon steel that undergoes a transformation known as eutectoid reaction. This reaction occurs at a specific temperature and results in the formation of a microstructure called pearlite. The percentage of carbon present in eutectoid steel is crucial in determining its properties and behavior.
Explanation:
To answer the given question, we need to understand the composition of eutectoid steel and its carbon percentage.
Eutectoid Reaction:
The eutectoid reaction occurs in iron-carbon alloys, specifically at a temperature of approximately 727°C (1341°F). At this temperature, the steel undergoes a phase change from austenite to pearlite. During this reaction, the carbon molecules redistribute and form layers of cementite within the ferrite matrix.
Carbon Percentage in Eutectoid Steel:
The composition of eutectoid steel is such that it contains exactly 0.76% carbon. This specific carbon percentage is critical because it allows the eutectoid reaction to occur at the eutectoid temperature.
Options:
a) 0.02% - This carbon percentage is significantly lower than the required 0.76% for eutectoid steel.
b) 0.3% - This carbon percentage is also lower than the required 0.76% for eutectoid steel.
c) 0.63% - This carbon percentage is still lower than the required 0.76% for eutectoid steel.
d) 0.8% - This carbon percentage is slightly higher than the required 0.76% for eutectoid steel. It is the correct answer.
e) 1.2% - This carbon percentage is higher than the required 0.76% for eutectoid steel.
Conclusion:
The correct answer for the percentage of carbon in eutectoid steel is option 'D' - 0.8%. This carbon percentage allows the eutectoid reaction to occur at the eutectoid temperature, resulting in the formation of pearlite microstructure.
Wrought iron- a)is a ductile material
- b)can be easily forged or welded
- c)cannot stand sudden and excessive shocks
- d)all of these
Correct answer is option 'D'. Can you explain this answer?
Wrought iron
a)
is a ductile material
b)
can be easily forged or welded
c)
cannot stand sudden and excessive shocks
d)
all of these
|
|
Sagarika Patel answered |
A tough malleable form of iron suitable for forging or rolling rather than casting, obtained by puddling pig iron while molten. It is nearly pure but contains some slag in the form of filaments.
1. It is used for pipe making due to its superior corrosion and fatigue resistance and better welding and threading qualities.
2. It is used for making bars for stay bolts, engine bolts and rivets etc. because properties demanded in these applications are corrosion and fatigue resistance.
3. For making iron doors, railings and fences.
4. For making plates.
5. For making special chains and crane hooks due to its good weldability and high impact strength.
6. It is also used extensively for general forging applications.
The unique property of cast iron is its high- a)malleability
- b)ductility
- c)surface finish
- d)damping characteristics
- e)hardness
Correct answer is option 'D'. Can you explain this answer?
The unique property of cast iron is its high
a)
malleability
b)
ductility
c)
surface finish
d)
damping characteristics
e)
hardness
|
|
Shreya Choudhury answered |
The unique property of cast iron is its high damping characteristics.
Damping is the ability of a material to dissipate energy when subjected to mechanical vibrations or oscillations. It is an important property in many engineering applications as it helps to reduce vibrations, noise, and resonance.
Cast iron is a type of iron-carbon alloy that contains a higher percentage of carbon compared to other forms of iron. This higher carbon content gives cast iron its unique properties, including its high damping characteristics.
Explanation:
1. Definition of Damping:
Damping is the process of dissipating energy from mechanical vibrations or oscillations. It is a measure of the material's ability to absorb and dissipate energy, thereby reducing the amplitude of vibrations.
2. Importance of Damping:
Damping is crucial in various engineering applications to control vibrations and prevent damage to structures and equipment. Excessive vibrations can lead to fatigue failure, noise generation, and decreased performance. Therefore, materials with high damping characteristics are desirable in such applications.
3. Cast Iron's Composition:
Cast iron is primarily composed of iron, carbon, and other alloying elements such as silicon, manganese, and sulfur. The carbon content in cast iron is typically 2-4%, which is significantly higher than other forms of iron.
4. Microstructure of Cast Iron:
The high carbon content in cast iron results in the formation of graphite flakes within the microstructure. These graphite flakes act as internal boundaries, which impede the movement of dislocations and reduce the material's ability to deform plastically. This leads to the high rigidity and low ductility of cast iron.
5. Damping Mechanism in Cast Iron:
The presence of graphite flakes in cast iron contributes to its high damping characteristics. When subjected to vibrations or oscillations, the graphite flakes within the microstructure undergo internal friction and relative movement, dissipating energy in the form of heat. This internal friction mechanism is responsible for the high damping capacity of cast iron.
6. Applications of Cast Iron's Damping Characteristics:
Cast iron's high damping characteristics make it suitable for various applications, such as machine tool bases, engine blocks, and automotive components. In these applications, the damping capacity of cast iron helps to reduce vibrations, noise, and resonance, thereby improving the overall performance and reliability of the system.
In conclusion, the unique property of cast iron is its high damping characteristics. The presence of graphite flakes within the microstructure allows cast iron to dissipate energy efficiently, making it an ideal material for applications that require vibration control and noise reduction.
Damping is the ability of a material to dissipate energy when subjected to mechanical vibrations or oscillations. It is an important property in many engineering applications as it helps to reduce vibrations, noise, and resonance.
Cast iron is a type of iron-carbon alloy that contains a higher percentage of carbon compared to other forms of iron. This higher carbon content gives cast iron its unique properties, including its high damping characteristics.
Explanation:
1. Definition of Damping:
Damping is the process of dissipating energy from mechanical vibrations or oscillations. It is a measure of the material's ability to absorb and dissipate energy, thereby reducing the amplitude of vibrations.
2. Importance of Damping:
Damping is crucial in various engineering applications to control vibrations and prevent damage to structures and equipment. Excessive vibrations can lead to fatigue failure, noise generation, and decreased performance. Therefore, materials with high damping characteristics are desirable in such applications.
3. Cast Iron's Composition:
Cast iron is primarily composed of iron, carbon, and other alloying elements such as silicon, manganese, and sulfur. The carbon content in cast iron is typically 2-4%, which is significantly higher than other forms of iron.
4. Microstructure of Cast Iron:
The high carbon content in cast iron results in the formation of graphite flakes within the microstructure. These graphite flakes act as internal boundaries, which impede the movement of dislocations and reduce the material's ability to deform plastically. This leads to the high rigidity and low ductility of cast iron.
5. Damping Mechanism in Cast Iron:
The presence of graphite flakes in cast iron contributes to its high damping characteristics. When subjected to vibrations or oscillations, the graphite flakes within the microstructure undergo internal friction and relative movement, dissipating energy in the form of heat. This internal friction mechanism is responsible for the high damping capacity of cast iron.
6. Applications of Cast Iron's Damping Characteristics:
Cast iron's high damping characteristics make it suitable for various applications, such as machine tool bases, engine blocks, and automotive components. In these applications, the damping capacity of cast iron helps to reduce vibrations, noise, and resonance, thereby improving the overall performance and reliability of the system.
In conclusion, the unique property of cast iron is its high damping characteristics. The presence of graphite flakes within the microstructure allows cast iron to dissipate energy efficiently, making it an ideal material for applications that require vibration control and noise reduction.
Pure iron is the structure of- a)ferrite
- b)pearlite
- c)anstenite
- d)ferrite and cementite
- e)ferrite and pearlite
Correct answer is option 'A'. Can you explain this answer?
Pure iron is the structure of
a)
ferrite
b)
pearlite
c)
anstenite
d)
ferrite and cementite
e)
ferrite and pearlite
|
|
Ashwin Gupta answered |
Structure of Pure Iron: Ferrite
Pure iron typically has a body-centered cubic (BCC) crystal structure, known as ferrite. This crystal structure is formed by iron atoms arranged in a cubic lattice, with an iron atom at each corner and one in the center of the cube. Ferrite is the stable form of iron at room temperature and atmospheric pressure.
Explanation:
1. Ferrite:
Ferrite is the purest form of iron and has a relatively soft and ductile structure. It is the stable phase of iron at temperatures below 912°C (1674°F), known as the Curie temperature. Below this temperature, the iron atoms arrange themselves in a regular lattice structure, allowing for easy plastic deformation and high ductility. Ferrite is magnetic and exhibits ferromagnetic properties.
2. Other Phases:
While ferrite is the structure of pure iron, it can undergo phase transformations when alloyed or subjected to heat treatment. These phase transformations result in the formation of different microstructures, such as pearlite, austenite, and cementite.
- Pearlite: Pearlite is a two-phase microstructure consisting of alternating layers of ferrite and cementite. It is formed when austenite (a high-temperature phase of iron) is slowly cooled below the eutectoid temperature (~727°C or 1341°F). The transformation of austenite to pearlite occurs in a eutectoid reaction, resulting in a lamellar microstructure with improved strength and hardness compared to ferrite alone.
- Austenite: Austenite is the high-temperature phase of iron that exists above the Curie temperature of 912°C (1674°F). It has a face-centered cubic (FCC) crystal structure and is non-magnetic. Austenite can be retained at lower temperatures by alloying iron with certain elements, such as nickel or manganese.
- Cementite: Cementite, also known as iron carbide (Fe3C), is a hard and brittle compound of iron and carbon. It is the hardest constituent in steel and forms when austenite is rapidly cooled above the eutectoid temperature (~727°C or 1341°F). Cementite is a key component of pearlite and contributes to its increased strength.
In Summary:
The correct answer is option A: Ferrite. Pure iron has a ferrite structure, which is a body-centered cubic arrangement of iron atoms. While other phases, such as pearlite, austenite, and cementite, can be formed through alloying or heat treatment, ferrite is the stable form of iron at room temperature and atmospheric pressure.
Pure iron typically has a body-centered cubic (BCC) crystal structure, known as ferrite. This crystal structure is formed by iron atoms arranged in a cubic lattice, with an iron atom at each corner and one in the center of the cube. Ferrite is the stable form of iron at room temperature and atmospheric pressure.
Explanation:
1. Ferrite:
Ferrite is the purest form of iron and has a relatively soft and ductile structure. It is the stable phase of iron at temperatures below 912°C (1674°F), known as the Curie temperature. Below this temperature, the iron atoms arrange themselves in a regular lattice structure, allowing for easy plastic deformation and high ductility. Ferrite is magnetic and exhibits ferromagnetic properties.
2. Other Phases:
While ferrite is the structure of pure iron, it can undergo phase transformations when alloyed or subjected to heat treatment. These phase transformations result in the formation of different microstructures, such as pearlite, austenite, and cementite.
- Pearlite: Pearlite is a two-phase microstructure consisting of alternating layers of ferrite and cementite. It is formed when austenite (a high-temperature phase of iron) is slowly cooled below the eutectoid temperature (~727°C or 1341°F). The transformation of austenite to pearlite occurs in a eutectoid reaction, resulting in a lamellar microstructure with improved strength and hardness compared to ferrite alone.
- Austenite: Austenite is the high-temperature phase of iron that exists above the Curie temperature of 912°C (1674°F). It has a face-centered cubic (FCC) crystal structure and is non-magnetic. Austenite can be retained at lower temperatures by alloying iron with certain elements, such as nickel or manganese.
- Cementite: Cementite, also known as iron carbide (Fe3C), is a hard and brittle compound of iron and carbon. It is the hardest constituent in steel and forms when austenite is rapidly cooled above the eutectoid temperature (~727°C or 1341°F). Cementite is a key component of pearlite and contributes to its increased strength.
In Summary:
The correct answer is option A: Ferrite. Pure iron has a ferrite structure, which is a body-centered cubic arrangement of iron atoms. While other phases, such as pearlite, austenite, and cementite, can be formed through alloying or heat treatment, ferrite is the stable form of iron at room temperature and atmospheric pressure.
Corrosion resistance of steel is increased by addition of- a)chromium and nickel
- b)sulphur, phosphorus, lead
- c)vanadium, aluminium
- d)tungsten, molybdenum, vanadium, chromium
- e)zinc
Correct answer is option 'A'. Can you explain this answer?
Corrosion resistance of steel is increased by addition of
a)
chromium and nickel
b)
sulphur, phosphorus, lead
c)
vanadium, aluminium
d)
tungsten, molybdenum, vanadium, chromium
e)
zinc
|
Anushka Bose answered |
Corrosion resistance of steel is increased by addition of chromium and nickel.
Explanation:
- Corrosion resistance: Corrosion is a process in which metals are gradually deteriorated by chemical reactions with their surroundings. Corrosion can lead to the weakening and failure of metal structures. Therefore, it is important to enhance the corrosion resistance of steel, which is a commonly used material in various industries.
- Chromium: Chromium is a key element in stainless steel, which is known for its excellent corrosion resistance. When chromium is added to steel, it reacts with oxygen in the air to form a thin, invisible layer of chromium oxide on the surface of the steel. This layer acts as a barrier, preventing further corrosion and protecting the underlying steel from environmental factors such as moisture and chemicals.
- Nickel: Nickel is another element commonly added to steel to improve its corrosion resistance. Nickel enhances the passivity of steel by promoting the formation of a stable oxide layer on the surface. This oxide layer acts as a protective barrier against corrosion, similar to the chromium oxide layer.
- Synergistic effect: The combination of chromium and nickel in steel creates a synergistic effect, resulting in significantly improved corrosion resistance compared to steel without these alloying elements. The chromium and nickel work together to enhance the formation and stability of the oxide layer, providing long-lasting protection against corrosion.
- Other elements: While other elements such as sulphur, phosphorus, lead, vanadium, aluminium, tungsten, molybdenum, and zinc can also influence the properties of steel, they do not have the same significant impact on corrosion resistance as chromium and nickel. Some of these elements may even have detrimental effects on corrosion resistance or other mechanical properties of steel.
- Conclusion: In summary, the addition of chromium and nickel to steel greatly improves its corrosion resistance. These alloying elements promote the formation of a protective oxide layer on the surface of the steel, preventing further corrosion and ensuring the durability and longevity of steel structures.
Explanation:
- Corrosion resistance: Corrosion is a process in which metals are gradually deteriorated by chemical reactions with their surroundings. Corrosion can lead to the weakening and failure of metal structures. Therefore, it is important to enhance the corrosion resistance of steel, which is a commonly used material in various industries.
- Chromium: Chromium is a key element in stainless steel, which is known for its excellent corrosion resistance. When chromium is added to steel, it reacts with oxygen in the air to form a thin, invisible layer of chromium oxide on the surface of the steel. This layer acts as a barrier, preventing further corrosion and protecting the underlying steel from environmental factors such as moisture and chemicals.
- Nickel: Nickel is another element commonly added to steel to improve its corrosion resistance. Nickel enhances the passivity of steel by promoting the formation of a stable oxide layer on the surface. This oxide layer acts as a protective barrier against corrosion, similar to the chromium oxide layer.
- Synergistic effect: The combination of chromium and nickel in steel creates a synergistic effect, resulting in significantly improved corrosion resistance compared to steel without these alloying elements. The chromium and nickel work together to enhance the formation and stability of the oxide layer, providing long-lasting protection against corrosion.
- Other elements: While other elements such as sulphur, phosphorus, lead, vanadium, aluminium, tungsten, molybdenum, and zinc can also influence the properties of steel, they do not have the same significant impact on corrosion resistance as chromium and nickel. Some of these elements may even have detrimental effects on corrosion resistance or other mechanical properties of steel.
- Conclusion: In summary, the addition of chromium and nickel to steel greatly improves its corrosion resistance. These alloying elements promote the formation of a protective oxide layer on the surface of the steel, preventing further corrosion and ensuring the durability and longevity of steel structures.
Weld decay is the phenomenon found with- a)cast iron
- b)mild steel
- c)non-ferrous materials
- d)wrought iron
- e)stainless steel
Correct answer is option 'E'. Can you explain this answer?
Weld decay is the phenomenon found with
a)
cast iron
b)
mild steel
c)
non-ferrous materials
d)
wrought iron
e)
stainless steel
|
Diya Dasgupta answered |
Weld Decay in Stainless Steel
Weld decay is a phenomenon that occurs specifically in stainless steel welds. It refers to the loss of corrosion resistance in the heat-affected zone (HAZ) adjacent to the weld. This can lead to localized corrosion and decreased mechanical properties in the affected area.
Causes of Weld Decay
Weld decay is primarily caused by the formation of chromium carbides in the HAZ during the welding process. Stainless steel contains chromium, which provides its corrosion resistance. However, when the steel is heated to high temperatures during welding, chromium can combine with carbon to form chromium carbides.
The formation of chromium carbides depletes the stainless steel of chromium, reducing its corrosion resistance in the affected area. This can result in the formation of localized corrosion, such as intergranular corrosion or pitting, leading to weld decay.
Prevention and Control
Several measures can be taken to prevent or control weld decay in stainless steel welds:
1. Selection of the Right Filler Material: Choosing a filler material with a low carbon content can help minimize the formation of chromium carbides. Filler materials, such as type 347 or type 316L, are commonly used for welding stainless steel to reduce the risk of weld decay.
2. Proper Heat Input: Controlling the heat input during welding is crucial to minimize the formation of chromium carbides. High heat input can increase the risk of carbide precipitation, while low heat input can result in incomplete fusion or poor weld quality. It is important to follow the recommended welding parameters to achieve a balance.
3. Post-Weld Heat Treatment: Applying post-weld heat treatment, such as solution annealing or stress relieving, can help dissolve the chromium carbides and restore the corrosion resistance of the stainless steel. This process involves heating the welded assembly to a specific temperature and holding it for a certain period of time, followed by controlled cooling.
4. Pickling and Passivation: After welding, the stainless steel should be properly cleaned and passivated to remove any contaminants and restore the protective chromium oxide layer on the surface. Pickling with an acid solution and passivation with a suitable chemical treatment can help prevent or mitigate weld decay.
Conclusion
Weld decay is a specific phenomenon that occurs in stainless steel welds due to the formation of chromium carbides in the heat-affected zone. It can lead to a loss of corrosion resistance and decreased mechanical properties in the affected area. By selecting the right filler material, controlling the heat input, applying post-weld heat treatment, and properly cleaning and passivating the weld, weld decay can be prevented or controlled, ensuring the integrity and performance of stainless steel welds.
Weld decay is a phenomenon that occurs specifically in stainless steel welds. It refers to the loss of corrosion resistance in the heat-affected zone (HAZ) adjacent to the weld. This can lead to localized corrosion and decreased mechanical properties in the affected area.
Causes of Weld Decay
Weld decay is primarily caused by the formation of chromium carbides in the HAZ during the welding process. Stainless steel contains chromium, which provides its corrosion resistance. However, when the steel is heated to high temperatures during welding, chromium can combine with carbon to form chromium carbides.
The formation of chromium carbides depletes the stainless steel of chromium, reducing its corrosion resistance in the affected area. This can result in the formation of localized corrosion, such as intergranular corrosion or pitting, leading to weld decay.
Prevention and Control
Several measures can be taken to prevent or control weld decay in stainless steel welds:
1. Selection of the Right Filler Material: Choosing a filler material with a low carbon content can help minimize the formation of chromium carbides. Filler materials, such as type 347 or type 316L, are commonly used for welding stainless steel to reduce the risk of weld decay.
2. Proper Heat Input: Controlling the heat input during welding is crucial to minimize the formation of chromium carbides. High heat input can increase the risk of carbide precipitation, while low heat input can result in incomplete fusion or poor weld quality. It is important to follow the recommended welding parameters to achieve a balance.
3. Post-Weld Heat Treatment: Applying post-weld heat treatment, such as solution annealing or stress relieving, can help dissolve the chromium carbides and restore the corrosion resistance of the stainless steel. This process involves heating the welded assembly to a specific temperature and holding it for a certain period of time, followed by controlled cooling.
4. Pickling and Passivation: After welding, the stainless steel should be properly cleaned and passivated to remove any contaminants and restore the protective chromium oxide layer on the surface. Pickling with an acid solution and passivation with a suitable chemical treatment can help prevent or mitigate weld decay.
Conclusion
Weld decay is a specific phenomenon that occurs in stainless steel welds due to the formation of chromium carbides in the heat-affected zone. It can lead to a loss of corrosion resistance and decreased mechanical properties in the affected area. By selecting the right filler material, controlling the heat input, applying post-weld heat treatment, and properly cleaning and passivating the weld, weld decay can be prevented or controlled, ensuring the integrity and performance of stainless steel welds.
In acidic bessemer process, the furnace is lined with- a)silica bricks
- b)a mixture of tar and burnt dolomite bricks
- c)either (a) or (b)
- d)none of these
Correct answer is option 'A'. Can you explain this answer?
In acidic bessemer process, the furnace is lined with
a)
silica bricks
b)
a mixture of tar and burnt dolomite bricks
c)
either (a) or (b)
d)
none of these
|
|
Tanishq Rane answered |
Acidic Bessemer Process
The Bessemer process is a method used for the mass production of steel. It involves the conversion of pig iron into steel by blowing air through it in a converter. The process can be carried out in either an acidic or basic environment, depending on the lining material used in the converter.
In the acidic Bessemer process, the furnace is lined with silica bricks. These bricks are made from silica, which is a compound of silicon and oxygen. Silica bricks have a high silica content, typically around 95%, and are able to withstand the high temperatures and harsh conditions of the converter.
Reasons for using Silica Bricks:
1. Acidic Environment: In the acidic Bessemer process, the lining material must be able to resist the corrosive effects of the acidic slag formed during the conversion of pig iron to steel. Silica bricks are highly resistant to acid corrosion, making them suitable for this purpose.
2. Thermal Insulation: Silica bricks have excellent thermal insulation properties, which help to maintain the high temperature required for the conversion process. They have low thermal conductivity, meaning that they are able to retain heat and prevent it from escaping the converter.
3. Chemical Stability: Silica bricks are chemically stable and do not react with the molten metal or slag during the conversion process. This stability ensures that the lining material does not deteriorate or contaminate the steel being produced.
4. Durability: Silica bricks have a high melting point and can withstand the extreme temperatures inside the converter. They are also able to withstand the mechanical stresses and strains that occur during the blowing of air through the molten metal.
5. Availability and Cost: Silica is a widely available and relatively low-cost material, making silica bricks a cost-effective choice for lining the converter in the acidic Bessemer process.
In conclusion, the correct answer is option 'A' - the furnace is lined with silica bricks in the acidic Bessemer process. These bricks provide the necessary acid resistance, thermal insulation, chemical stability, durability, and cost-effectiveness required for the successful conversion of pig iron into steel.
The Bessemer process is a method used for the mass production of steel. It involves the conversion of pig iron into steel by blowing air through it in a converter. The process can be carried out in either an acidic or basic environment, depending on the lining material used in the converter.
In the acidic Bessemer process, the furnace is lined with silica bricks. These bricks are made from silica, which is a compound of silicon and oxygen. Silica bricks have a high silica content, typically around 95%, and are able to withstand the high temperatures and harsh conditions of the converter.
Reasons for using Silica Bricks:
1. Acidic Environment: In the acidic Bessemer process, the lining material must be able to resist the corrosive effects of the acidic slag formed during the conversion of pig iron to steel. Silica bricks are highly resistant to acid corrosion, making them suitable for this purpose.
2. Thermal Insulation: Silica bricks have excellent thermal insulation properties, which help to maintain the high temperature required for the conversion process. They have low thermal conductivity, meaning that they are able to retain heat and prevent it from escaping the converter.
3. Chemical Stability: Silica bricks are chemically stable and do not react with the molten metal or slag during the conversion process. This stability ensures that the lining material does not deteriorate or contaminate the steel being produced.
4. Durability: Silica bricks have a high melting point and can withstand the extreme temperatures inside the converter. They are also able to withstand the mechanical stresses and strains that occur during the blowing of air through the molten metal.
5. Availability and Cost: Silica is a widely available and relatively low-cost material, making silica bricks a cost-effective choice for lining the converter in the acidic Bessemer process.
In conclusion, the correct answer is option 'A' - the furnace is lined with silica bricks in the acidic Bessemer process. These bricks provide the necessary acid resistance, thermal insulation, chemical stability, durability, and cost-effectiveness required for the successful conversion of pig iron into steel.
Pig iron is the name given to- a)raw material for blast furnace
- b)product of blast furnace made by reduction of iron ore
- c)iron containing huge quantitities of carbon
- d)iron in molten form in the ladles
- e)iron scrap
Correct answer is option 'B'. Can you explain this answer?
Pig iron is the name given to
a)
raw material for blast furnace
b)
product of blast furnace made by reduction of iron ore
c)
iron containing huge quantitities of carbon
d)
iron in molten form in the ladles
e)
iron scrap
|
|
Lakshmi Datta answered |
Pig iron is the name given to:
Pig iron is a term used in the iron and steel industry to refer to a specific product obtained from the blast furnace process. It is an intermediate product that serves as a raw material for the production of various types of iron and steel products. The correct answer to the question is option B, which states that pig iron is the product of the blast furnace made by the reduction of iron ore.
Explanation:
The process of producing pig iron involves the reduction of iron ore in a blast furnace. Here is a detailed explanation of the process and the characteristics of pig iron:
1. Raw material for blast furnace:
- Iron ore, coke (a form of carbon derived from coal), and limestone are the primary raw materials used in a blast furnace.
- Iron ore is the main source of iron and contains various impurities such as silica, alumina, and phosphorus.
- Coke is used as a fuel and provides the necessary heat for the chemical reactions in the furnace.
- Limestone acts as a flux, helping to remove impurities and adjust the chemical composition of the molten iron.
2. Blast furnace process:
- The raw materials are charged into the blast furnace from the top.
- The furnace is heated to a high temperature, typically around 1600°C (2900°F).
- The coke reacts with the oxygen in the air to produce carbon monoxide, which acts as a reducing agent.
- The carbon monoxide reacts with the iron ore, reducing the iron oxide to metallic iron.
- The impurities present in the iron ore combine with the flux to form slag, which floats on top of the molten iron.
3. Pig iron production:
- The molten iron collected at the bottom of the blast furnace is known as pig iron.
- Pig iron is highly carbon-rich, containing around 4-5% carbon along with other impurities.
- It has a high melting point and is quite brittle.
- Pig iron is not suitable for most applications directly but serves as a key raw material for further refining processes to produce various types of iron and steel products.
In summary, pig iron is an intermediate product obtained from the blast furnace process by reducing iron ore with carbon monoxide. It is a carbon-rich form of iron that requires further processing to remove impurities and adjust its composition for specific applications in the iron and steel industry.
Pig iron is a term used in the iron and steel industry to refer to a specific product obtained from the blast furnace process. It is an intermediate product that serves as a raw material for the production of various types of iron and steel products. The correct answer to the question is option B, which states that pig iron is the product of the blast furnace made by the reduction of iron ore.
Explanation:
The process of producing pig iron involves the reduction of iron ore in a blast furnace. Here is a detailed explanation of the process and the characteristics of pig iron:
1. Raw material for blast furnace:
- Iron ore, coke (a form of carbon derived from coal), and limestone are the primary raw materials used in a blast furnace.
- Iron ore is the main source of iron and contains various impurities such as silica, alumina, and phosphorus.
- Coke is used as a fuel and provides the necessary heat for the chemical reactions in the furnace.
- Limestone acts as a flux, helping to remove impurities and adjust the chemical composition of the molten iron.
2. Blast furnace process:
- The raw materials are charged into the blast furnace from the top.
- The furnace is heated to a high temperature, typically around 1600°C (2900°F).
- The coke reacts with the oxygen in the air to produce carbon monoxide, which acts as a reducing agent.
- The carbon monoxide reacts with the iron ore, reducing the iron oxide to metallic iron.
- The impurities present in the iron ore combine with the flux to form slag, which floats on top of the molten iron.
3. Pig iron production:
- The molten iron collected at the bottom of the blast furnace is known as pig iron.
- Pig iron is highly carbon-rich, containing around 4-5% carbon along with other impurities.
- It has a high melting point and is quite brittle.
- Pig iron is not suitable for most applications directly but serves as a key raw material for further refining processes to produce various types of iron and steel products.
In summary, pig iron is an intermediate product obtained from the blast furnace process by reducing iron ore with carbon monoxide. It is a carbon-rich form of iron that requires further processing to remove impurities and adjust its composition for specific applications in the iron and steel industry.
Gamma iron exits at following temperature- a)room temperature
- b)near melting point
- c)between 1400ºC and 1539ºC
- d)between 910ºC and 1400ºC
- e)none of the above
Correct answer is option 'D'. Can you explain this answer?
Gamma iron exits at following temperature
a)
room temperature
b)
near melting point
c)
between 1400ºC and 1539ºC
d)
between 910ºC and 1400ºC
e)
none of the above
|
|
Dishani Desai answered |
Gamma iron, also known as austenite, is a high-temperature phase of iron that has a face-centered cubic (FCC) crystal structure. It is stable at elevated temperatures and undergoes a phase transformation to alpha iron (ferrite) at lower temperatures. The temperature range at which gamma iron exists depends on the specific conditions.
The correct answer is option 'D', which states that gamma iron exists between 910°C and 1400°C.
Explanation:
1. Room Temperature:
At room temperature (typically around 25°C), iron is in the alpha iron phase, which has a body-centered cubic (BCC) crystal structure. Gamma iron is not stable at room temperature and will not exist under normal conditions.
2. Near Melting Point:
As the temperature increases towards the melting point of iron (1538°C), the proportion of gamma iron increases. However, at the very near melting point, the majority of the iron will be in the liquid phase rather than the gamma iron phase. Therefore, it is incorrect to say that gamma iron exists "near" the melting point.
3. Between 1400°C and 1539°C:
In this temperature range, the gamma iron phase is still present. However, it is important to note that the exact temperature at which the phase transformation to alpha iron occurs depends on factors such as alloy composition, cooling rate, and presence of impurities. The temperature range given in option 'C' includes both the gamma and alpha iron phases.
4. Between 910°C and 1400°C:
This temperature range is commonly referred to as the "austenitic range" for iron. Within this range, gamma iron is the stable phase, and it exists in a single-phase state. This means that all of the iron is in the gamma iron phase, without any transformation to alpha iron. Therefore, option 'D' is the correct answer.
In conclusion, gamma iron exists between 910°C and 1400°C, which is the austenitic range for iron. It is important to consider the specific temperature range and conditions when discussing the existence of gamma iron.
The correct answer is option 'D', which states that gamma iron exists between 910°C and 1400°C.
Explanation:
1. Room Temperature:
At room temperature (typically around 25°C), iron is in the alpha iron phase, which has a body-centered cubic (BCC) crystal structure. Gamma iron is not stable at room temperature and will not exist under normal conditions.
2. Near Melting Point:
As the temperature increases towards the melting point of iron (1538°C), the proportion of gamma iron increases. However, at the very near melting point, the majority of the iron will be in the liquid phase rather than the gamma iron phase. Therefore, it is incorrect to say that gamma iron exists "near" the melting point.
3. Between 1400°C and 1539°C:
In this temperature range, the gamma iron phase is still present. However, it is important to note that the exact temperature at which the phase transformation to alpha iron occurs depends on factors such as alloy composition, cooling rate, and presence of impurities. The temperature range given in option 'C' includes both the gamma and alpha iron phases.
4. Between 910°C and 1400°C:
This temperature range is commonly referred to as the "austenitic range" for iron. Within this range, gamma iron is the stable phase, and it exists in a single-phase state. This means that all of the iron is in the gamma iron phase, without any transformation to alpha iron. Therefore, option 'D' is the correct answer.
In conclusion, gamma iron exists between 910°C and 1400°C, which is the austenitic range for iron. It is important to consider the specific temperature range and conditions when discussing the existence of gamma iron.
Silicon in cast iron- a)makes the iron soft and easily machinable
- b)increases harness and brittleness
- c)makes the iron white and hard
- d)aids fusibility and fluidity
Correct answer is option 'A'. Can you explain this answer?
Silicon in cast iron
a)
makes the iron soft and easily machinable
b)
increases harness and brittleness
c)
makes the iron white and hard
d)
aids fusibility and fluidity
|
Ruchi Ahuja answered |
Effect of Silicon in Cast Iron
Silicon in cast iron plays a crucial role in determining its properties. Let's discuss how silicon affects cast iron in detail:
Makes the iron soft and easily machinable
- Silicon helps to improve the machinability of cast iron by making it softer. This makes it easier to shape and machine the cast iron into the desired form.
Increases hardness and brittleness
- Contrary to the previous point, silicon can also increase the hardness of cast iron, making it more brittle. This can be advantageous in certain applications where hardness is desired.
Makes the iron white and hard
- Silicon can contribute to the formation of white cast iron, which is characterized by its hardness. This type of cast iron is often used in applications where wear resistance is crucial.
Aids fusibility and fluidity
- Silicon helps to improve the fusibility and fluidity of cast iron during the casting process. This means that the molten iron can flow more easily into the mold, resulting in better casting quality.
Therefore, while silicon can have various effects on cast iron, including making it softer and more machinable, as well as increasing hardness and brittleness, its overall impact depends on the specific requirements of the application.
Silicon in cast iron plays a crucial role in determining its properties. Let's discuss how silicon affects cast iron in detail:
Makes the iron soft and easily machinable
- Silicon helps to improve the machinability of cast iron by making it softer. This makes it easier to shape and machine the cast iron into the desired form.
Increases hardness and brittleness
- Contrary to the previous point, silicon can also increase the hardness of cast iron, making it more brittle. This can be advantageous in certain applications where hardness is desired.
Makes the iron white and hard
- Silicon can contribute to the formation of white cast iron, which is characterized by its hardness. This type of cast iron is often used in applications where wear resistance is crucial.
Aids fusibility and fluidity
- Silicon helps to improve the fusibility and fluidity of cast iron during the casting process. This means that the molten iron can flow more easily into the mold, resulting in better casting quality.
Therefore, while silicon can have various effects on cast iron, including making it softer and more machinable, as well as increasing hardness and brittleness, its overall impact depends on the specific requirements of the application.
Chilled cast iron is produced- a)by adding magnesium to molten cast iron
- b)by quick cooling of molten cast iron
- c)from white cast iron by annealing process
- d)none of these
Correct answer is option 'B'. Can you explain this answer?
Chilled cast iron is produced
a)
by adding magnesium to molten cast iron
b)
by quick cooling of molten cast iron
c)
from white cast iron by annealing process
d)
none of these
|
|
Jyoti Deshpande answered |
Chilled Cast Iron
Chilled cast iron is a type of cast iron that is produced by quick cooling of molten cast iron. This process is also known as "chilling" and results in a hard, wear-resistant surface layer on the cast iron. Chilled cast iron is widely used in the production of machine tool beds, rolls for rolling mills, and other applications where wear resistance is important.
Production Process
The production process for chilled cast iron involves the following steps:
1. Melting: Cast iron is melted in a furnace at high temperatures.
2. Alloying: Alloying elements such as carbon, silicon, and manganese are added to the melted cast iron to improve its properties.
3. Pouring: The molten cast iron is then poured into a mold.
4. Cooling: The mold is cooled quickly by spraying water onto it. This causes the molten cast iron to cool rapidly and solidify.
5. Chilling: The surface of the cast iron is chilled by the rapid cooling, resulting in a hard, wear-resistant layer.
Advantages
Chilled cast iron offers several advantages over other materials:
1. Wear resistance: Chilled cast iron has a hard, wear-resistant surface layer that makes it ideal for use in applications where wear is a concern.
2. Machinability: Chilled cast iron is easy to machine, making it ideal for use in machine tool beds and other applications where precise machining is required.
3. Cost-effective: Chilled cast iron is a cost-effective alternative to other materials such as steel, which can be more expensive.
Conclusion
Chilled cast iron is a type of cast iron that is produced by quick cooling of molten cast iron. This process results in a hard, wear-resistant surface layer on the cast iron, making it ideal for use in applications where wear is a concern. Chilled cast iron is widely used in the production of machine tool beds, rolls for rolling mills, and other applications where wear resistance is important.
Chilled cast iron is a type of cast iron that is produced by quick cooling of molten cast iron. This process is also known as "chilling" and results in a hard, wear-resistant surface layer on the cast iron. Chilled cast iron is widely used in the production of machine tool beds, rolls for rolling mills, and other applications where wear resistance is important.
Production Process
The production process for chilled cast iron involves the following steps:
1. Melting: Cast iron is melted in a furnace at high temperatures.
2. Alloying: Alloying elements such as carbon, silicon, and manganese are added to the melted cast iron to improve its properties.
3. Pouring: The molten cast iron is then poured into a mold.
4. Cooling: The mold is cooled quickly by spraying water onto it. This causes the molten cast iron to cool rapidly and solidify.
5. Chilling: The surface of the cast iron is chilled by the rapid cooling, resulting in a hard, wear-resistant layer.
Advantages
Chilled cast iron offers several advantages over other materials:
1. Wear resistance: Chilled cast iron has a hard, wear-resistant surface layer that makes it ideal for use in applications where wear is a concern.
2. Machinability: Chilled cast iron is easy to machine, making it ideal for use in machine tool beds and other applications where precise machining is required.
3. Cost-effective: Chilled cast iron is a cost-effective alternative to other materials such as steel, which can be more expensive.
Conclusion
Chilled cast iron is a type of cast iron that is produced by quick cooling of molten cast iron. This process results in a hard, wear-resistant surface layer on the cast iron, making it ideal for use in applications where wear is a concern. Chilled cast iron is widely used in the production of machine tool beds, rolls for rolling mills, and other applications where wear resistance is important.
Chilled cast iron has- a)no graphite
- b)a very high percentage of graphite
- c)a low percentage of graphite
- d)graphite as its basic constituent of composition
- e)none of the above is true
Correct answer is option 'A'. Can you explain this answer?
Chilled cast iron has
a)
no graphite
b)
a very high percentage of graphite
c)
a low percentage of graphite
d)
graphite as its basic constituent of composition
e)
none of the above is true
|
Kiran Basu answered |
Chilled Cast Iron Composition
Chilled cast iron refers to a specific type of cast iron that is rapidly cooled or "chilled" during the casting process. This rapid cooling results in a unique microstructure with certain characteristics.
No Graphite Presence
One of the key features of chilled cast iron is that it does not contain any graphite. Graphite is a common constituent in most forms of cast iron, but in chilled cast iron, the rapid cooling prevents the formation of graphite.
Microstructure
Due to the rapid cooling process, the carbon in the cast iron solidifies in the form of cementite, rather than graphite. This results in a microstructure that is predominantly made up of cementite and ferrite, rather than graphite flakes.
Properties
Chilled cast iron typically has high hardness and wear resistance due to the absence of graphite. It is often used in applications where high wear resistance is required, such as in the production of cutting tools, rolls for rolling mills, or wear-resistant components.
Conclusion
In conclusion, chilled cast iron does not contain any graphite and has a unique microstructure that sets it apart from other forms of cast iron. Its properties make it well-suited for specific applications where high wear resistance is necessary.
Chilled cast iron refers to a specific type of cast iron that is rapidly cooled or "chilled" during the casting process. This rapid cooling results in a unique microstructure with certain characteristics.
No Graphite Presence
One of the key features of chilled cast iron is that it does not contain any graphite. Graphite is a common constituent in most forms of cast iron, but in chilled cast iron, the rapid cooling prevents the formation of graphite.
Microstructure
Due to the rapid cooling process, the carbon in the cast iron solidifies in the form of cementite, rather than graphite. This results in a microstructure that is predominantly made up of cementite and ferrite, rather than graphite flakes.
Properties
Chilled cast iron typically has high hardness and wear resistance due to the absence of graphite. It is often used in applications where high wear resistance is required, such as in the production of cutting tools, rolls for rolling mills, or wear-resistant components.
Conclusion
In conclusion, chilled cast iron does not contain any graphite and has a unique microstructure that sets it apart from other forms of cast iron. Its properties make it well-suited for specific applications where high wear resistance is necessary.
'Killed steels' are those steels- a)which are destroyed by turning
- b)which after their destruction are recycled to produce fresh steel
- c)which are doxidised in the ladle with silicon and aluminium
- d)in which carbon is completely burnt
- e)which have poor properties due to improper manufacturing
Correct answer is option 'C'. Can you explain this answer?
'Killed steels' are those steels
a)
which are destroyed by turning
b)
which after their destruction are recycled to produce fresh steel
c)
which are doxidised in the ladle with silicon and aluminium
d)
in which carbon is completely burnt
e)
which have poor properties due to improper manufacturing
|
|
Dipika Bose answered |
Introduction:
Killed steels are a type of steel that undergoes a specific process during manufacturing. This process involves adding specific elements to the steel to improve its properties and make it more suitable for certain applications. In this answer, we will discuss the correct answer option 'C' and explain why it is the correct choice.
Explanation:
The correct answer is option 'C', which states that killed steels are those steels that are deoxidized in the ladle with silicon and aluminum. Let's understand why this is the correct answer.
Deoxidation:
Deoxidation is an important process in steelmaking, especially for increasing the quality and properties of the steel. During the steelmaking process, impurities such as oxygen can be present in the molten steel. These impurities can adversely affect the steel's properties and performance. Deoxidation is performed to remove these impurities and improve the steel's quality.
Killed Steels:
Killed steels are produced by adding deoxidizing agents to the molten steel in the ladle. These deoxidizing agents, such as silicon and aluminum, react with the oxygen present in the steel to form stable compounds. This reaction removes the oxygen from the steel, preventing the formation of undesirable oxides and improving the steel's properties.
Benefits of Deoxidization:
Deoxidizing the steel has several benefits, including:
1. Improved Mechanical Properties: Deoxidation helps in eliminating harmful impurities, resulting in improved mechanical properties such as strength, toughness, and ductility.
2. Enhanced Weldability: Deoxidized steels have better weldability as the elimination of impurities reduces the chances of defects and improves the quality of weld joints.
3. Improved Surface Quality: Deoxidation helps in reducing surface defects, such as porosity and scale, resulting in a smoother and more uniform surface finish.
4. Better Corrosion Resistance: Deoxidized steels have improved resistance to corrosion due to the removal of harmful oxides that can promote corrosion.
Conclusion:
In conclusion, killed steels are those steels that undergo deoxidation in the ladle using deoxidizing agents such as silicon and aluminum. This process removes impurities and improves the steel's properties, making it more suitable for various applications. Deoxidized steels have improved mechanical properties, weldability, surface quality, and corrosion resistance.
Killed steels are a type of steel that undergoes a specific process during manufacturing. This process involves adding specific elements to the steel to improve its properties and make it more suitable for certain applications. In this answer, we will discuss the correct answer option 'C' and explain why it is the correct choice.
Explanation:
The correct answer is option 'C', which states that killed steels are those steels that are deoxidized in the ladle with silicon and aluminum. Let's understand why this is the correct answer.
Deoxidation:
Deoxidation is an important process in steelmaking, especially for increasing the quality and properties of the steel. During the steelmaking process, impurities such as oxygen can be present in the molten steel. These impurities can adversely affect the steel's properties and performance. Deoxidation is performed to remove these impurities and improve the steel's quality.
Killed Steels:
Killed steels are produced by adding deoxidizing agents to the molten steel in the ladle. These deoxidizing agents, such as silicon and aluminum, react with the oxygen present in the steel to form stable compounds. This reaction removes the oxygen from the steel, preventing the formation of undesirable oxides and improving the steel's properties.
Benefits of Deoxidization:
Deoxidizing the steel has several benefits, including:
1. Improved Mechanical Properties: Deoxidation helps in eliminating harmful impurities, resulting in improved mechanical properties such as strength, toughness, and ductility.
2. Enhanced Weldability: Deoxidized steels have better weldability as the elimination of impurities reduces the chances of defects and improves the quality of weld joints.
3. Improved Surface Quality: Deoxidation helps in reducing surface defects, such as porosity and scale, resulting in a smoother and more uniform surface finish.
4. Better Corrosion Resistance: Deoxidized steels have improved resistance to corrosion due to the removal of harmful oxides that can promote corrosion.
Conclusion:
In conclusion, killed steels are those steels that undergo deoxidation in the ladle using deoxidizing agents such as silicon and aluminum. This process removes impurities and improves the steel's properties, making it more suitable for various applications. Deoxidized steels have improved mechanical properties, weldability, surface quality, and corrosion resistance.
Chapter doubts & questions for Manufacturing Engineering - Mechanical Engineering SSC JE (Technical) 2025 is part of Mechanical Engineering exam preparation. The chapters have been prepared according to the Mechanical Engineering exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for Mechanical Engineering 2025 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.
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Mechanical Engineering SSC JE (Technical)
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