Correct option is C
Carburizing is a heat treatment process used for case hardening, where the outer layer of a steel component is enriched with carbon to increase its hardness. The process involves exposing the part to a carbon-rich environment at high temperatures, allowing carbon to diffuse into the surface layer while the core remains tough and ductile.
This heat treatment applied to low carbon steel parts after machining at well as high alloy steel bearing, gear and other components.
Annealing process heating the steel to a temperature below the upper critical temperature
Tempering improve toughness of steel.
