Heat treatment annealing is a kind of process which is often used in hot working of metal workpiece. It can effectively improve the plasticity, hardness and internal stress of metal workpiece. Include steel sheet annealing, steel bar annealing ,steel tube annealing.
The main purpose of the annealing heat treatment is to:
(1) reduce the hardness of the steel and improve the plasticity, so as to facilitate the processing of cutting and cold deformation;
(2) refine the structure and components of the crystal grains and the uniform steel, improve the performance of the steel or prepare for subsequent heat treatment;
(3) The residual internal stress in the steel is eliminated to prevent deformation and cracking. The annealing method includes full annealing, homogenization annealing, spheroidizing annealing, destress degradation, recrystallization annealing, dehydrogen annealing, and the like.
(1) complete annealing. When the steel is heated to 30 ℃ above Ac3 for 50 ℃, after complete austenitizing, the process of slowly cooling and obtaining nearly equilibrium microstructure is called complete annealing. It is mainly used in castings of medium carbon steel and medium carbon alloy steel. Its action is to refine the grain, uniform structure, and eliminate the stress.
(2) spheroidization annealing. Annealing for spheroidization of carbides in steel is called spheroidization annealing. It is mainly suitable for pre-heat treatment of eutectic steel and hypereutectic steel used in manufacturing die and die. After spheroidizing annealing, the hardness is reduced and it is easy to be machined. Moreover, the austenite grain is not easy to be coarse when quenched and heated, and the deformation and cracking tendency of the workpiece is small when the workpiece is cooled.
(3) stress-free annealing. The workpiece is heated to about 500 ℃ for a period of time, then cooled to 200 ℃ and then cooled by air. The aim is to remove internal stress, stabilize size and reduce deformation.
Overseas manager: Tom Wang
Phone: 0086-13303078975(whatsapp, wechat,line)
Specialist of bar heat treatment furnace in China; Glad to be your business partner in induction heating field.
Post time: 04-28-2019