Heat the hypo-eutectoid steel to the above temperature, hold it for enough time to make the steel completely austenitization and make the composition basically uniform, and then slowly cool it to obtain a heat treatment process with a structure close to equilibrium. Its purpose is to eliminate structural defects, eliminate stress and soften steel, so as to facilitate cutting and plastic deformation processing. The heating temperature of is usually above 20-30 ° C. However, if steel contains strong carbide forming elements, the heating temperature should be properly increased to make alloy carbide dissolve into austenite quickly. When steel contains elements that are easy to coarsen grains, such as manganese, the annealing temperature should be slightly reduced. The microstructure of hypo-eutectoid steel after full annealing is ferrite and pearlite? Its shape, distribution, and quantity are related to the cooling rate.
No classification at present.