Consider the following statements relating to mechanical properties of ceramics:1. Tensile strength is theoretically high but in practice quite low.
2. Compressive strength is many times lower than tensile strength.
3. Shear strength is high.
4. Transverse strength is easy to ascertain.Which of the statements given above are correct?
Ans. (a) 2. Compressive strength is many times higher than tensile strength.
1. They contain both metallic and non-metallic elements.
2. Characterized by their higher resistance to high temperatures and harsh environments than metals and polymers.
3. Typically good insulators to passage of both heat and electricity.
4. Less dense than most metals and alloys.
5. They are harder and stiffer, but brittle in nature.
6. They are mostly oxides, nitrides, and carbides of metals.
7. Wide range: traditional (clay, silicate glass, cement) to advanced (carbides, pure oxides, non-silicate glasses).
Cast steel crankshaft surface is hardened by
Hardness of steel greatly improves with
Which one of the following is correct?
When "devitrification" of inorganic glasses is done,
Ans. (c) Inorganic glasses can be made to transform from a non crystalline state to one that crystalline by the proper high – temperature heat treatment which is called devitrification.
Major operations in the manufacture of steel balls used for Ball bearings are givenbelow
1. Oil lapping
2. Cold heading
5. Rough grinding
The correct sequence of these operations is
Assertion (A): Carburizing is done on non-ferrous alloys to increase the surfacehardness.
Reason (R): Precipitation hardening of non-ferrous alloys involves solution heattreatment followed by precipitation heat treatment.
Ans. (d) A is false. Carburizing is done only on ferrous alloys to increase the surface
hardenss but it is not done on non-
Which one of the following pairs is correctly matched?
Which one of the following elements/ alloy exhibits season cracking?
i. Copper alloys cracks in ammonaical solution (Season Cracking)
ii. Stainless steel and Aluminium cracks in the presence of chlorides, Steel cracks in the presence of alkali (Boiler Cracking) or Caustic Cracking.
Induction hardening is basically a
Which one among the following is the most effective strengthening mechanism ofnon-ferrous metal?
Guideways of lathe beds are hardened by
In case carburising Carbon is introduced to form a high carbon layer at thesurface. The carbon is introduce in the form of
Temperature required for full annealing in hyper-eutectoid steel is
Match List I (Name of treatment) with List II (Media used) and select the correct answer using the codes given below the Lists
List I List II
A. Pack carburizing 1. Ammonia gas
B. Gas carburizing 2. Sodium cyanide
C. Cyaniding 3. Carburizing compound
D. Nitriding 4. Ethane
Codes: A B C D A B C D
(a) 3 4 2 1 (b) 2 1 3 4
(c) 3 1 2 4 (d) 2 4 3 1
Globular form of cementite in the structure of steel is obtained through
The complete phase recrystallization and fine grain structure is obtained incasting, forging and rolled parts by:
Assertion (A): Normalized steel will have lower hardness than annealed steel.Reason (R): The pearlite of normalized steel is finer and has lower intermolecularspace.
Which of the following statements are true of annealing of steels?
1. Steels are heated to 500 to 700°C.
2. Cooling is done slowly and steadily.
3. Internal stresses are relieved.
4. Ductility of steel is increased.
Select the correct answer using the codes given below:
Ans. (a) Steels are heated to 30 to 50°C above the upper critical temperature.
The pattern known as Widmanstatten structure is encountered in:
Heating the hypoeutectoid steels to 30oC above the upper critical temperatureline, soaking at that temperature and then cooling slowly to room temperature toform a pearlite and ferrite structure, is known as
Ans. (d) The process described is annealing.
Tempering is a process of annealing
Match List I with List II and select the correct answer using the codes given below the lists:
List I (Heat treatment) List II (Effect on the properties)
A. Annealing 1. Refined grain structure
B. Nitriding 2. Improves the hardness of the whole mass
C. Martempering 3. Increases surface hardness
D. Normalising 4. Improves ductility
Codes: A B C D A B C D
(a) 4 3 2 1 (b) 1 3 4 2
c) 4 2 1 3 (d) 2 1 3 4
Consider the following pairs:
Heat treatment Effect on medium carbon steel
1. Normalizing : Grain refinement
2. Full annealing : Uniform grain structure
3. Martempering : Decreased ductility
4. Spheroidizing : Maximum softness
Which of the pairs given above are correctly matched?
Which of the following generally decreases in the steel after quench-hardening?
2. Percentage elongation
3. Impact strength
Austempering is employed to obtain:
Consider the following quenching media:
3. Water + NaOH
4. BrineThe correct sequence of these media in order of increasing hardness of steel undergoing heattreatment is
'Tempering' of quenched martensitic steel is necessary to improve the
Match List-I (Effect of Cooling) with List-II (Cooling Medium) and select the correct answer using the code given below:
List -I List - II
A. Martensite 1. Water quenched
B. Very fine pearlite 2. Air cooled
C. Fine pearlite 3. Furnace cooled
D. Coarse pearlite 4. Oil quenched
A B C D A B C D
(a) 1 4 2 3 (b) 2 3 1 4
(c) 2 3 4 1 (d) 1 2 3 4
Two cooling curves A andB for a eutectoid ironcarbonalloy are superimposed on acontinuous cooling transformation diagram as shown in the given figure.Fine pearlite micro structureis represented by the points labelled
Ans. (c) Fine pearlite structure is formed below eutectoid temperature and on moderate cooling.
Which one of the following mediums is used for the fastest cooling rate of steel quenching?
Ans. (d) Comparative cooling rates
Brine has fastest cooling rate of steel quenching and is also used as secondary refrigerant.