ANS:B - cold working

Hardness and tensile strength of austenitic stainless steel can be increased by cold working. Cold working, also known as cold forming or cold deformation, involves plastic deformation of the metal at room temperature or slightly below its recrystallization temperature. This process leads to an increase in dislocation density and a change in the microstructure of the material, resulting in improved mechanical properties such as hardness and tensile strength. Martempering, normalizing, and hardening are heat treatment processes that are typically applied to other types of steels, such as carbon steels or some alloy steels, to achieve specific mechanical properties. However, these processes are not commonly used for austenitic stainless steel because it is not responsive to conventional heat treatments due to its high nickel and chromium content. Instead, cold working is the primary method used to increase hardness and tensile strength in austenitic stainless steel.