Common annealing process
1. Complete annealing. It is used to refine the coarse superheated structure of medium and low carbon steel which has poor mechanical properties after casting, forging and welding. The workpiece is heated to a temperature of 30 to 50 ° C above the temperature at which all of the ferrite is transformed into austenite, and is kept for a period of time, and then slowly cooled with the furnace, and the austenite is again transformed during the cooling process, so that the microstructure of the steel is thinned. 2. Spheroidizing annealing. It is used to reduce the high hardness of tool steel and bearing steel after forging. The workpiece is heated to a temperature of 20 to 40 ° C above the temperature at which the steel begins to form austenite, and is slowly cooled after the heat preservation. During the cooling process, the lamellar cementite in the pearlite becomes spherical, thereby lowering the hardness. 3. Isothermal annealing. It is used to reduce the high hardness of certa...