Views: 0 Author: Kevin Publish Time: 2024-11-07 Origin: Site
Commonly used annealing processes have the following categories:
1. Complete annealing. It is used to refine the coarse superheated structure with poor mechanical properties after casting, forging and welding of medium and low carbon steel. The workpiece is heated to the temperature of 30~50℃ above which the ferrite is all transformed into austenite, and the heat is kept for a period of time, and then the austenite is slowly cooled with the furnace, and the austenite is transformed again during the cooling process, which can make the structure of the steel thinner.
2. Spheroidizing annealing. Used to reduce the high hardness of tool steel and bearing steel after forging. The workpiece is heated to 20~40℃ above the temperature at which the steel begins to form austenite, and slowly cooled after heat preservation. During the cooling process, the laminate cementite in the pearlite becomes spherical, thereby reducing the hardness.
3, such as nirvana annealing. It is used to reduce the high hardness of some alloy structural steels with high nickel and chromium content for cutting. Generally, the austenite is cooled at a faster rate to a more unstable temperature, and the heat preservation time is appropriate, and the austenite is transformed into totensite or sortensite, and the hardness can be reduced.
4. Recrystallization annealing. It is used to eliminate the hardening phenomenon of metal wire and sheet in the process of cold drawing and cold rolling (increasing hardness and decreasing plasticity). The heating temperature is generally 50 to 150 ° C below the temperature at which the steel begins to form austenite, and only in this way can the work hardening effect be eliminated to soften the metal.
5, graphitization annealing. It is used to change cast iron containing a lot of cementite into good plasticity malleable cast iron. The process operation is to heat the casting to about 950 ° C, and properly cool it after holding it for a certain time, so that the cementite decomposes to form a flocculent graphite.
6, diffusion annealing. It is used to homogenize the chemical composition of alloy castings and improve their performance. The method is to heat the casting to the highest possible temperature without melting, and hold it for a long time, and slow cooling after the diffusion of various elements in the alloy tends to be evenly distributed.
7, stress relief annealing. Used to relieve the internal stress of steel castings and welded parts. For steel products after heating begins to form austenite temperature below 100~200℃, after heat preservation in the air cooling, you can eliminate the internal stress.
The online bright annealing equipment developed by Hngao Technology chooses medium frequency induction heating power supply and adopts DSP+IGBT structure with more optimized effect.
DSP digital control system, with perfect self-protection and self-diagnosis function, smaller volume, faster heating, and higher energy saving characteristics.
Before production, the inert gas is filled into the equipment, the air in the equipment is emptied to avoid pollution. After the pipe is welded and polished, it enters the online annealing equipment, and the sealing card is closed. When the heating furnace is used, the induction power supply starts to work, and the pipe is heated until it is stable at 1050℃, and the annealing is carried out. The cooling section mainly uses graphite kits to ensure the rapid conduction of heat, so that the pipe is cooled, and uses high-purity hydrogen for protection, to ensure that the high-brightness of the annealed pipe is cooled down after the welding pipe is exported to the sealing protection card, and the entire annealing process is completed.