Annealing is a heat treatment process in which steel or other ferrous materials are heated to a specified temperature, held for a controlled period and then cooled slowly inside the furnace. This controlled thermal cycle refines the microstructure, reduces hardness, relieves residual stresses and improves ductility. Unlike hardening processes that increase surface hardness, annealing prepares components for machining, forming, welding or subsequent heat treatment by producing a softer and more uniform structure.

Annealing is widely used to restore workability after cold working and to improve dimensional stability before precision manufacturing operations.