Why should steel be annealed

Annealing: Annealing is a metal heat treatment process in which the metal is slowly heated to a certain temperature, maintained for a sufficient time, and then cooled at a suitable rate (usually slow cooling, sometimes controlled cooling).

The purpose of annealing is to soften the material or workpiece after casting, forging, welding or cutting, improve plasticity and toughness, homogenize chemical composition, remove residual stress, or obtain expected physical properties. There are various annealing processes depending on the purpose, such as isothermal annealing, homogenization annealing, spheroidizing annealing, stress relief annealing, recrystallization annealing, stabilization annealing, magnetic field annealing and so on.

The effects of annealing: (1) Reduce hardness and improve machinability; (2) Eliminate residual stress, stabilize dimensions, and reduce deformation and crack tendency; (3) Refine grains, adjust organization, and eliminate organizational defects. In production, the annealing process is widely used. According to the different purposes of annealing required by the workpiece, there are various process specifications for annealing, and commonly used are complete annealing, spheroidizing annealing, and stress relief annealing.