This set of Heat Treatment of Metals and Alloys Multiple Choice Questions & Answers (MCQs) focuses on “Steels Processes – Diffusion Annealing”.
1. What is the main purpose of diffusion annealing?
a) To relieve internal stresses
b) To remove structural non uniformity
c) To improve ductility
d) To increase brittleness
View Answer
Explanation: The main purpose of diffusion annealing is to remove structural non uniformity. The main purpose of stress relieving is to reduce internal stresses. The main purpose of full annealing is to improve ductility and reduce brittleness.
2. Which one of the following statements is correct regarding temperature range diffusion annealing?
a) 600-700°C
b) 400-500°C
c) 800-1000°C
d) 1000-1200°C
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Explanation: In case of diffusion annealing, steel is heated to a temperature of 1000-1200°C. For full annealing, steel is heated to a temperature above upper critical temperature. For stress relieving, steel is heated to a temperature below lower critical temperature.
3. Which one of the following statements is correct regarding holding time of diffusion annealing?
a) 1-2 hours
b) 10-20 hours
c) 4-5 hours
d) 5-8 hours
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Explanation: The holding time for diffusion annealing is too long. It is generally 10-20 hours for diffusion annealing. It is then followed by slow cooling.
4. Diffusion annealing is also known as _________ annealing.
a) partial
b) subcritical
c) homogenizing
d) process
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Explanation: Diffusion annealing is also known as homogenizing annealing. It is employed to remove structural non uniformity. It is done for both hyper and hypoeutectoid steels.
5. Which one of the following statements is incorrect regarding diffusion annealing?
a) It requires heating to a high temperature
b) It requires long holding time
c) It is very cheap
d) It is very expensive
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Explanation: Diffusion annealing requires heating to very high temperatures. Then holding is done for a long time followed by slow cooling. Because of these factors, diffusion annealing is a very expensive process.
6. Which one of the following statements is incorrect regarding the cooling rate in diffusion annealing?
a) It requires heating to a high temperature
b) It requires long holding time
c) It leads to excessive scaling
d) It does not lead to excessive scaling
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Explanation: Diffusion annealing requires heating to very high temperatures. Then holding is done for a long time followed by slow cooling. Because of these factors, diffusion annealing is a very expensive process. Because of high temperature large scaling takes place.
7. Which one of the following statements is incorrect regarding the cooling rate in diffusion annealing?
a) It is very expensive
b) It requires long holding time
c) It leads to excessive scaling
d) Secondary heat treatment is not required after this
View Answer
Explanation: Diffusion annealing requires heating to very high temperatures. Then holding is done for a long time followed by slow cooling. Because of these factors, diffusion annealing is a very expensive process. Because of high temperature large scaling takes place. Because of all these factors, a second heat treatment process is also required after this.
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.
