Tempering is defined as reheating quenched steel to a suitable temperature for an appropriate period of time and then cooling back to room temperature.

• A. Reheating above transformation temperature
• B. Rapid quenching
• C. Reheating quenched steel to suitable temp and cooling
• D. Cold rolling

Answer: (C)

Tempering involves reheating the quenched steel to a lower, specific temperature for a set period and then cooling back to room temperature. After quenching, steel is very hard but brittle because of the martensitic structure and residual stresses. Heating to a tempering temperature allows limited diffusion and redistribution of alloying elements and carbides, relieving stresses and reducing brittleness while preserving most of the hardness. The described process exactly matches tempering. Reheating above the transformation temperature would transform the structure again in a way that tempering does not, rapid quenching is the prior hardening step, and cold rolling is a mechanical deformation process, not a heat-treatment sequence aimed at adjusting microstructure.