This set of Heat Treatment of Metals and Alloys Multiple Choice Questions & Answers (MCQs) focuses on “Steels Processes – Isothermal Annealing”.
1. Which one of the following statements is correct regarding isothermal annealing?
a) Steel is heated to a temperature above upper critical temperature for hypereutectoid steel
b) Steel is heated to a temperature above upper critical temperature for hypoeutectoid steel
c) Steel is heated to a temperature above upper critical temperature for eutectoid steel
d) Steel is heated to a temperature above lower critical temperature for hypoeutectoid steel
View Answer
Explanation: In the case of isothermal annealing, steel is heated to a temperature above upper critical temperature just like in the case of full annealing. It is held at this temperature for some time and then cooled to a temperature below the lower critical temperature.
2. Which one of the following statements is correct regarding isothermal annealing?
a) Steel is held at a temperature above upper critical temperature for hypereutectoid steel
b) Steel is held at a temperature above lower critical temperature for hypereutectoid steel
c) Steel is held at a temperature above upper critical temperature for eutectoid steel
d) Steel is held at a temperature above upper critical temperature for hypoeutectoid steel
View Answer
Explanation: In the case of isothermal annealing, hypoeutectoid steel is heated to a temperature above upper critical temperature just like in the case of full annealing. It is held at this temperature for some time and then cooled to a temperature below lower critical temperature.
3. Which one of the following statements is correct regarding isothermal annealing?
a) Steel is held at a temperature above upper critical temperature for hypereutectoid steel
b) Steel is held at a temperature above lower critical temperature for hypereutectoid steel
c) Steel is held at a temperature above upper critical temperature for eutectoid steel
d) Steel is held at a temperature above lower critical temperature for eutectoid steel
View Answer
Explanation: In the case of isothermal annealing, eutectoid steel is heated to a temperature above lower critical temperature just like in the case of full annealing. It is held at this temperature for some time and then cooled to a temperature below lower critical temperature.
4. Which one of the following statements is correct regarding isothermal annealing?
a) Steel is held at a temperature above upper critical temperature for hypereutectoid steel
b) Steel is held at a temperature above lower critical temperature for hypereutectoid steel
c) Steel is held at a temperature above upper critical temperature for eutectoid steel
d) Steel is held at a temperature below lower critical temperature for eutectoid steel
View Answer
Explanation: In case of isothermal annealing, eutectoid steel is heated to a temperature above lower critical temperature. It is held at this temperature for some time and then cooled to a temperature below lower critical temperature. Then it is held at this temperature for some time followed by air cooling.
5. Which one of the following statements is correct regarding isothermal annealing?
a) Steel is held at a temperature above upper critical temperature for hypereutectoid steel
b) Steel is held at a temperature above lower critical temperature for hypereutectoid steel
c) Steel is held at a temperature above upper critical temperature for eutectoid steel
d) Steel is held at a temperature below lower critical temperature for hypoeutectoid steel
View Answer
Explanation: In case of isothermal annealing, hypoeutectoid steel is heated to a temperature above upper critical temperature. It is held at this temperature for some time and then cooled to a temperature below lower critical temperature. Then it is held at this temperature for some time followed by air cooling.
6. Which one of the following statements is correct regarding the cooling rate in isothermal annealing?
a) Air cooling is done during cooling from above upper critical temperature to below lower critical temperature
b) Steel is cooled at a rapid rate from above upper critical temperature to below lower critical temperature
c) Steel is cooled at a very slow rate from above upper critical temperature to below lower critical temperature
d) Steel is cooled in a single furnace from above upper critical temperature to below lower critical temperature
View Answer
Explanation: In case of isothermal annealing, hypoeutectoid steel is heated to a temperature above upper critical temperature. It is held at this temperature for some time and then cooled to a temperature below lower critical temperature at a very rapid rate by quickly transferring it to other furnace at the required temperature.
7. The time taken in isothermal annealing is shorter than full annealing.
a) True
b) False
View Answer
Explanation: In the case of isothermal annealing, the time is cut short as compared to full annealing. The reason is that it involves fast cooling at one stage and slow cooling at the other.
8. In isothermal annealing we get a more homogeneous structure than full annealing.
a) True
b) False
View Answer
Explanation: Isothermal annealing is a modified version of full annealing. Therefore we get a much more homogeneous structure in case of isothermal annealing because transformation takes place at a uniform temperature.
9. Which one of the following statements is correct regarding isothermal annealing?
a) Any type of steel component can be treated by this process
b) It is suitable for only small sized components
c) It is suitable for only heavy components
d) It is suitable for both small and heavy components
View Answer
Explanation: One important limitation of isothermal annealing is that it cannot be treated for heavy components. The reason is that it is not possible to cool them rapidly and uniformly at a temperature at which transformation occurs.
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.
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