This set of Tough Materials Science Questions and Answers focuses on “Mechanical Behavior of Iron-Carbon Alloys”.
1. In an iron carbon alloy, the mechanical properties are dependent on the micro structure.
a) True
b) False
View Answer
Explanation: The above statement is true. In an iron carbon alloy, the mechanical properties are dependent on the micro structure.
2. Which of the following is present in pearlite?
a) Spherodite
b) Bainite
c) Ledeburite
d) Ferrite
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Explanation: Pearlite consists of alternate layer of ferrite and cementite in which cementite is harder and more brittle as compared to ferrite.
3. Which of the following is true?
a) Fine pearlite is harder than coarse pearlite
b) Fine pearlite is softer than coarse pearlite
c) Fine pearlite is more ductile than coarse pearlite
d) Toughness of steel decreases with increase in carbon percentage
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Explanation: Fine pearlite is harder than coarse pearlite, but coarse pearlite is more ductile than fine pearlite.
4. Which is the most tough among the steels given their carbon composition?
a) 0.1%
b) 0.2%
c) 1.5%
d) 2.5%
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Explanation: The toughness of the steel decreases as we increase the carbon content and therefore 0.1% carbon which is lower than 1.5%, 0.2% and 2.5% is most tough among the options.
5. Which of the following is present in spherodite?
a) Pearlite
b) Bainite
c) Ledeburite
d) Ferrite
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Explanation: Spherodite also consists of ferrite and cementite. In spherodite it cementite is present in a sphere structure in a matrix of ferrite.
6. Which of the following is present in bainite?
a) Ferrite
b) Bainite
c) Ledeburite
d) α-Ferrite
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Explanation: Bainite steels consists of α-Ferrite and cementite and have a finer structure which makes then stronger than pearlite steel.
7. Which among the following is the strongest?
a) Austenite
b) Pearlite
c) Bainite
d) Martensite
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Explanation: Among all the structure martensite has the strongest structure. It is the hardest and most brittle among the microstructure.
8. In which of the following steels there is a chance of quenching cracks being formed?
a) 0.2% carbon
b) 0.4% carbon
c) 0.5% carbon
d) 0.6% carbon
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Explanation: If the carbon content in a steel is higher than 0.5 %, during quenching there can be a formation of quenching cracks.
9. At what temperature is martensite heated in tempering? (in degree Celsius)
a) 727
b) 627
c) 327
d) 927
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Explanation: The martensitic steel is tempered in the temperature of 650–800°C to get optimum mechanical properties that includes ductility and toughness.
10. Tempered martensite has better ductility than martensite.
a) True
b) False
View Answer
Explanation: Tempered martensite has better ductility than martensite due to tempering. The hardness of the two is nearly the same.
Sanfoundry Global Education & Learning Series – Materials Science.
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