This set of Heat Treatment of Metals and Alloys Multiple Choice Questions & Answers (MCQs) focuses on “Steels – Bainitic Transformation”.
1. Bainite is a mixture of which of the following phases?
a) Ferrite and austenite
b) Ferrite and carbide
c) Austenite and cementite
d) Austenite and carbide
View Answer
Explanation: Bainite is a mixture of ferrite and carbide. Mixture of ferrite and cementite is called pearlite. Sometimes bainite also contains a mixture of ferrite and cementite.
2. Bainite is lamellar in structure.
a) True
b) False
View Answer
Explanation: Bainite is not lamellar in structure. This is a basic difference between bainite and pearlite. Pearlite has a lamellar structure. Bainite is accicular and feathery structure.
3. Which one of the following statements is correct?
a) Higher magnifications are required for resolution of bainite than pearlite
b) Lower magnifications are required for resolution of bainite than pearlite
c) Equal magnifications are required for resolution of bainite and pearlite
d) Magnifications required for resolution of bainite and pearlite may be higher or lower
View Answer
Explanation: Higher magnifications are required for resolution of bainite than pearlite. The reason behind this is that in case of bainite the distribution of ferrite is much finer scale.
4. Which one of the following statements is correct regarding alloy steels which show sharp Bs temperature?
a) They do not have bainitic bay
b) They do not have pearlitic bay
c) They have separate pearlitic and bainitic bay
d) They have overlapping pearlitic and bainitic bay
View Answer
Explanation: Most of the alloy steels do not show sharp Bs temperature. Those steels which show sharp Bs temperature have a separate pearlitic and bainitic bay.
5. Which one of the following statements is correct?
a) Cooling rate for formation of bainite is greater than that for pearlite
b) Cooling rate for formation of bainite is lower than that for pearlite
c) Cooling rate for formation of bainite is equal to that for pearlite
d) Cooling rate for formation of bainite may be greater than or lower than that for pearlite
View Answer
Explanation: Cooling rate for formation of bainite is greater than that for pearlite. The cooling rate obtained by drawing tangent at the nose is CCR. Thus for the formation of bainite cooling rate should be sufficiently grater than that for pearlite so as to suppress the formation of pearlite.
6. Bainite is formed by continuous cooling.
a) True
b) False
View Answer
Explanation: In those carbon steels where pearlitic and bainitic bays overlap, unlike martensite or pearlite, Bainite cannot be formed by continuous cooling. Isothermal cooling is done in these cases.
Sanfoundry Global Education & Learning Series – Heat Treatment of Metals and Alloys.
To practice all areas of Heat Treatment of Metals and Alloys, here is complete set of Multiple Choice Questions and Answers.
