Question

Which of the following heat treatment processes is/are used for surface hardening of steels?

• A. Carburizing
• B. Cyaniding
• C. Annealing
• D. Carbonitriding

Hint:

Surface hardening processes like carburizing and carbonitriding introduce carbon (and nitrogen in the case of carbonitriding) into the surface, making it harder and more wear-resistant. Annealing is used for softening materials.

Answer 1

The Correct Option is A, B, D

- (A) Carburizing: This statement is TRUE. Carburizing is a surface hardening process where the steel is heated in the presence of carbon to increase the carbon content at the surface. This process improves the hardness of the surface while maintaining a tougher core.
- (B) Cyaniding: This statement is TRUE. Cyaniding is similar to carburizing but uses a cyanide bath, which introduces both carbon and nitrogen to the surface of the steel, making it harder and more wear-resistant.
- (C) Annealing: This statement is FALSE. Annealing is a heat treatment process used to soften the material, improve ductility, and relieve internal stresses. It is not used for surface hardening.
- (D) Carbonitriding: This statement is TRUE. Carbonitriding is a surface hardening process where steel is exposed to both carbon and nitrogen in a controlled environment. This process improves both surface hardness and wear resistance.
Hence, the correct options are (A), (B), and (D).