Question 215General Subjects - Assistant Engineer

The correct answer is D) tempering. Tempering is the process of reheating a hardened component to a temperature lower than the hardening temperature, and then cooling it. This process is done to reduce the brittleness of the hardened component and increase its toughness and ductility. The other options are incorrect because: A) Case hardening is a different process that involves the introduction of carbon or nitrogen into the surface of a metal component to increase its hardness. B) Low temperature hardening refers to the initial hardening process, not the subsequent tempering. C) Annealing is the process of heating a metal to a high temperature and then slowly cooling it to relieve internal stresses and increase its softness.