Annealing is a kind of heat treatment process for materials, which refers to slowly heating the metal to a certain temperature, and then cooling it at an appropriate rate after a certain time. Its advantage is to reduce hardness and improve machinability; Eliminate residual stress, stabilize size, reduce deformation and crack tendency; Refine the grain, adjust the structure and eliminate the structural defects.
The annealing process of stainless steel is mainly divided into three types: complete annealing, spheroidizing annealing and stress relief annealing.
- Complete annealing. Heat the stainless steel for a period of time to make its internal structure completely austenitized. After holding it at 30~50 ℃ for a period of time, cool it with room temperature.
- Spheroidizing annealing. When the stainless steel is heated to the beginning of forming austenite, it shall be kept at 20~40 ℃ for a period of time, and then slowly cooled. During cooling, lamellar cementite in pearlite inside it will become spherical.
- Evenly arrange the stainless steel belt on the feeding frame, wait for the conveyor belt to send it to the annealing furnace, heat it to 1050~1080 ℃ under the protection of a controlled atmosphere, and then keep it warm for a short period of time until the carbide precipitated from austenite is completely dissolved in the austenite structure, and quickly cool it to below 350 ℃.