Annealing is a heat treatment wherein a material is altered, causing changes in its properties such as strength and hardness. It is a process that produces conditions by heating to above the recrystallization temperature and maintaining a suitable temperature, and then cooling. Annealing is used to induce ductility, soften material, relieve internal stresses, refine the structure by making it homogeneous, and improve cold working properties.

In the cases of steel, this process is performed by substantially heating the material (generally until glowing) for a while and allowing it to cool. In this fashion the metal is softened and prepared for further work such as shaping, stamping, or forming. ZX had 6 large equipments for annealing.