This set of Heat Treatment of Metals and Alloys Multiple Choice Questions & Answers (MCQs) focuses on “Steels Processes – Full Annealing”.
1. Which one of the following statements is correct regarding full annealing?
a) Steel is heated to a temperature of 30-50°C above upper critical temperature for hypereutectoid steel
b) Steel is heated to a temperature of 30-50°C above upper critical temperature for hypoeutectoid steel
c) Steel is heated to a temperature of 10-20°C above upper critical temperature for hypereutectoid steel
d) Steel is heated to a temperature of 30-50°C above lower critical temperature for hypoeutectoid steel
View Answer
Explanation: For hypoeutectoid steel, steel is heated to a temperature 30-50°C above the upper critical temperature to get a homogeneous austenitic structure. This is followed by holding for sufficient time to ensure proper homogenization. Then it is followed by slow cooling.
2. Which one of the following statements is correct regarding full annealing?
a) Steel is heated to a temperature of 30-50°C above upper critical temperature for hypereutectoid steel
b) Steel is heated to a temperature of 30-50°C above upper critical temperature for eutectoid steel
c) Steel is heated to a temperature of 10-20°C above upper critical temperature for hypereutectoid steel
d) Steel is heated to a temperature of 30-50°C above lower critical temperature for eutectoid steel
View Answer
Explanation: Steel is heated to a temperature of 30-50°C above lower critical temperature for eutectoid steel. For eutectoid steel we can get austenitic structure at temperatures above lower critical temperature.
3. Which one of the following statements is incorrect regarding full annealing?
a) It is employed for eutectoid steel
b) It is employed for hypoeutectoid steel
c) It is employed for hypereutectoid steel
d) The cooling rate is very slow
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Explanation: Full annealing is not generally employed for hypereutectoid steel. The reason is that heating above upper critical temperature will lead to grain coarsening which will lead to poor mechanical properties which is not desirable.
4. Which one of the following statements is correct regarding full annealing?
a) The austenitic grain size attains its minimum value just below upper critical temperature for hypereutectoid steel
b) The austenitic grain size attains its minimum value just below upper critical temperature for hypoeutectoid steel
c) The austenitic grain size attains its minimum value just above upper critical temperature for hypereutectoid steel
d) The austenitic grain size attains its minimum value just above upper critical temperature for hypoeutectoid steel
View Answer
Explanation: The austenitic grain size attains its minimum value just above the upper critical temperature for hypoeutectoid steel. This is the reason why hypoeutectoid steel is heated to a temperature 30-50°C above the upper critical temperature.
5. Which one of the following statements is incorrect regarding full annealing?
a) It is very time taking
b) It is very cheap
c) It is very expensive
d) It has lesser industrial use than normalizing
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Explanation: Because of the fact that full annealing involves prolonged heat treatment cycles, it makes it quite expensive. Greater the time involved, more will be the time for which heating and cooling be done thus lead to high cost.
6. What is the final product of full annealing?
a) Fine austenite
b) Fine pearlite
c) Coarse pearlite
d) Coarse austenite
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Explanation: The main purpose of full annealing is to improve ductility and reduce hardness. Therefore the final product is coarse pearlite. Fine pearlite will lead to the formation of a hard and brittle structure whereas in coarse pearlite, hardness decreases and ductility increases.
7. Which one of the following statements is correct regarding full annealing?
a) Steel is heated to a temperature of 30-50°C above upper critical temperature for hypereutectoid steel
b) Steel is heated to a temperature of 30-50°C above upper critical temperature for eutectoid steel
c) Steel is heated to a temperature of 10-20°C above upper critical temperature for hypereutectoid steel
d) Steel is heated to a temperature of 30-50°C above lower critical temperature for hypereutectoid steel
View Answer
Explanation: Steel is heated to a temperature of 30-50°C above the lower critical temperature for hypereutectoid steel. For hypereutectoid steel if we heat it above the upper critical temperature as in the case of hypoeutectoid steel, it will lead to grain coarsening.
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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