Topic: Material Science
Which of the following treatment does not improve hardness?
- A. Quenching
- B. Cyaniding
- C. Normalizing
- D. Annealing
Answer: D. Annealing
Explanation: Annealing is a stress relieving process. It does not improve hardness; instead, it is used to increase ductility and reduce hardness and strength. Quenching is a hardening process. Cyaniding increases surface hardness, and normalizing increases hardness compared to the annealing process.