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Microstructure of pearlite is composed of X% ferrite and Y% cementite. The value of X and Y is
- a)78 and 22
- b)50 and 50
- c)88 and 12
- d)90 and 10
Correct answer is option 'C'. Can you explain this answer?
Verified Answer
Microstructure of pearlite is composed of X% ferrite and Y% cementite....
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Microstructure of pearlite is composed of X% ferrite and Y% cementite....
The microstructure of pearlite is composed of two distinct phases: ferrite and cementite. Ferrite is a solid solution of carbon in iron, while cementite is a compound of iron and carbon. The percentages of ferrite and cementite in pearlite can vary depending on the composition of the steel and the cooling rate during its formation.
Explanation:
Pearlite is formed when austenite, a high-temperature phase of steel, is transformed into a eutectoid mixture of ferrite and cementite during the cooling process. The microstructure of pearlite consists of alternating layers of ferrite and cementite, giving it a unique appearance under a microscope.
The correct answer to the given question is option 'C', which states that the microstructure of pearlite is composed of 88% ferrite (X) and 12% cementite (Y). This composition is commonly observed in pearlite formed in hypoeutectoid steels, where the carbon content is below the eutectoid composition of 0.76%.
The percentage composition of pearlite can be explained by the lever rule, which relates the volume fractions of the two phases in a two-phase system. According to the lever rule, the volume fraction of a particular phase is equal to the weight fraction of that phase divided by its specific volume.
In the case of pearlite, the ferrite phase has a lower density than the cementite phase. Therefore, to maintain the mass balance, a larger volume fraction of ferrite is required compared to cementite. This results in a higher percentage of ferrite in the microstructure.
In hypoeutectoid steels, the carbon content is typically less than the eutectoid composition. As a result, during the transformation of austenite to pearlite, some of the excess carbon is trapped in the ferrite phase, leading to the formation of a carbon-rich cementite phase. This explains why the percentage of cementite in pearlite is relatively low (12%) compared to ferrite (88%) in option 'C'.
In summary, the microstructure of pearlite is composed of 88% ferrite and 12% cementite, as stated in option 'C'. This composition is commonly observed in hypoeutectoid steels, where the carbon content is below the eutectoid composition.
Explanation:
Pearlite is formed when austenite, a high-temperature phase of steel, is transformed into a eutectoid mixture of ferrite and cementite during the cooling process. The microstructure of pearlite consists of alternating layers of ferrite and cementite, giving it a unique appearance under a microscope.
The correct answer to the given question is option 'C', which states that the microstructure of pearlite is composed of 88% ferrite (X) and 12% cementite (Y). This composition is commonly observed in pearlite formed in hypoeutectoid steels, where the carbon content is below the eutectoid composition of 0.76%.
The percentage composition of pearlite can be explained by the lever rule, which relates the volume fractions of the two phases in a two-phase system. According to the lever rule, the volume fraction of a particular phase is equal to the weight fraction of that phase divided by its specific volume.
In the case of pearlite, the ferrite phase has a lower density than the cementite phase. Therefore, to maintain the mass balance, a larger volume fraction of ferrite is required compared to cementite. This results in a higher percentage of ferrite in the microstructure.
In hypoeutectoid steels, the carbon content is typically less than the eutectoid composition. As a result, during the transformation of austenite to pearlite, some of the excess carbon is trapped in the ferrite phase, leading to the formation of a carbon-rich cementite phase. This explains why the percentage of cementite in pearlite is relatively low (12%) compared to ferrite (88%) in option 'C'.
In summary, the microstructure of pearlite is composed of 88% ferrite and 12% cementite, as stated in option 'C'. This composition is commonly observed in hypoeutectoid steels, where the carbon content is below the eutectoid composition.
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Microstructure of pearlite is composed of X% ferrite and Y% cementite. The value of X and Y isa)78 and 22b)50 and 50c)88 and 12d)90 and 10Correct answer is option 'C'. Can you explain this answer? for Mechanical Engineering 2025 is part of Mechanical Engineering preparation. The Question and answers have been prepared according to the Mechanical Engineering exam syllabus. Information about Microstructure of pearlite is composed of X% ferrite and Y% cementite. The value of X and Y isa)78 and 22b)50 and 50c)88 and 12d)90 and 10Correct answer is option 'C'. Can you explain this answer? covers all topics & solutions for Mechanical Engineering 2025 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Microstructure of pearlite is composed of X% ferrite and Y% cementite. The value of X and Y isa)78 and 22b)50 and 50c)88 and 12d)90 and 10Correct answer is option 'C'. Can you explain this answer?.
Microstructure of pearlite is composed of X% ferrite and Y% cementite. The value of X and Y isa)78 and 22b)50 and 50c)88 and 12d)90 and 10Correct answer is option 'C'. Can you explain this answer? for Mechanical Engineering 2025 is part of Mechanical Engineering preparation. The Question and answers have been prepared according to the Mechanical Engineering exam syllabus. Information about Microstructure of pearlite is composed of X% ferrite and Y% cementite. The value of X and Y isa)78 and 22b)50 and 50c)88 and 12d)90 and 10Correct answer is option 'C'. Can you explain this answer? covers all topics & solutions for Mechanical Engineering 2025 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Microstructure of pearlite is composed of X% ferrite and Y% cementite. The value of X and Y isa)78 and 22b)50 and 50c)88 and 12d)90 and 10Correct answer is option 'C'. Can you explain this answer?.
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