Topic: Material Science
Which one is not the purpose of heat treatment of steels?
- A. Changing the composition of steel on the surface
- B. Changing the percentage of carbon and Si in the bulk.
- C. Increasing or decreasing the grain size
- D. Removing undesirable residual stresses
Answer: B. Changing the percentage of carbon and Si in the bulk.
Explanation: Changing the percentage of carbon and silicon in the bulk is not the purpose of heat treatment of steels.