Annealing is a metal heat treatment process in which the metal is slowly heated to a certain temperature, kept for a sufficient time, and then cooled at a suitable rate. Annealing heat treatment is divided into complete annealing, incomplete annealing and stress relief annealing, diffusion annealing, spheroidizing annealing, and recrystallization annealing. The mechanical properties of annealed materials can be tested by tensile test or hardness test. Many steels are supplied in the state of annealing and heat treatment. The hardness of the steel can be tested with a Rockwell hardness tester to test the HRB hardness. For thinner steel plates, steel strips and thin-walled steel pipes, a surface Rockwell hardness tester can be used to test the HRT hardness. .Heating the steel to a certain temperature above or below the critical point Ac1, holding it for a period of time, and then slowly cooling it in a furnace or buried in a furnace or a medium with poor thermal conductivity to obtain a stable structure close to the equilibrium state . Purpose 1. Improve or eliminate various structural defects and residual stress caused by steel in the process of casting, forging, rolling and welding, and prevent workpiece deformation and cracking; 2. Soften workpiece for cutting; 3. Refine grains and improve Structure to improve the mechanical properties of the workpiece; ④ Prepare the structure for the final heat treatment (quenching, tempering). Metal annealing Annealing process Complete annealing The purpose is to refine grains, uniform structure, eliminate internal stress and machining defects, reduce hardness, improve machinability and cold plastic deformation ability. It is used to refine the coarse superheated structure with poor mechanical properties after casting, forging and welding of medium and low carbon steel. Kehua heats the workpiece to a temperature of 30-50°C above the temperature at which all ferrite transforms into austenite, holds for a period of time, and then slowly cools with the furnace. During the cooling process, the austenite transforms again, which can change the structure of the steel. thin. Spheroidizing annealing is used to reduce the high hardness of tool steel and bearing steel after forging. The workpiece is heated to 20-40°C above the temperature at which the steel begins to form austenite, and then slowly cooled after heat preservation. During the cooling process, the lamellar cementite in the pearlite becomes spherical, thereby reducing the hardness. Isothermal annealing is used to reduce the high hardness of some alloy structural steels with high nickel and chromium content for cutting. Generally, it is first cooled to the most unstable temperature of austenite at a relatively fast rate, and the austenite is transformed into trosteite or sorbite for an appropriate time, and the hardness can be reduced. Metal annealing The above is the purpose and main process of metal annealing. I don't know if your friends understand it. If you think the editor is not detailed enough, you can visit Kehua's official website.