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What are the heat treatment processes

What are the heat treatment processes

1. Annealing operation method: After heating the steel to Ac3+30~50 degrees or Ac1+30~50 degrees or the temperature below Ac1 (relevant information can be consulted), generally cool slowly with the furnace temperature.

2. Normalizing operation method: heat the steel to 30~50 degrees above Ac3 or Accm, and cool it at a slightly higher cooling rate than annealing after heat preservation.

3. Quenching operation method: heat the steel to above the phase transition temperature Ac3 or Ac1, keep it for a period of time, and then quickly cool it in water, nitrate, oil, or air. Purpose: Quenching is generally to obtain a high-hardness martensitic structure. Sometimes, when quenching some high-alloy steels (such as stainless steel and wear-resistant steel), it is to obtain a single and uniform austenite structure to improve wear resistance. and corrosion resistance.

4. Tempering operation method: reheat the quenched steel to a certain temperature below Ac1, and cool it in air or oil, hot water or water after heat preservation.

5. Quenching and tempering operation method: high temperature tempering after quenching is called quenching and tempering, that is, heating the steel to a temperature 10~20 degrees higher than that of quenching, quenching after heat preservation, and then tempering at a temperature of 400~720 degrees.

6. Aging operation method: heat the steel to 80~200 degrees, keep the temperature for 5~20 hours or longer, and then take it out of the furnace and cool it in the air. Purpose: 1. Stabilize the structure of the steel after quenching, reduce the deformation during storage or use; 2. Reduce the internal stress after quenching and grinding, and stabilize the shape and size.

7. Operation method of cold treatment: Cool the quenched steel parts in a low temperature medium (such as dry ice, liquid nitrogen) to -60 to -80 degrees or lower, and then take out the uniform temperature to room temperature.

8. The operation method of flame heating surface quenching: the flame burning with oxygen-acetylene mixed gas is sprayed on the surface of the steel part, and it is heated rapidly. When the quenching temperature is reached, it is cooled by spraying water immediately.

9. Induction heating surface quenching operation method: put the steel part into the inductor to generate an induced current on the surface of the steel part, heat it to the quenching temperature in a very short time, and then spray water for cooling.

10. Carburizing operation method: Put the steel into the carburizing medium, heat it to 900-950 degrees and keep it warm, so that the steel surface can obtain a carburized layer with a certain concentration and depth.

11. Nitriding operation method: use the active nitrogen atoms decomposed by ammonia gas at 500 to 600 degrees to make the surface of the steel part saturated with nitrogen to form a nitrided layer.

12. Nitrocarburizing operation method: carburizing and nitriding simultaneously to the surface of the steel. Purpose: To improve the hardness, wear resistance, fatigue strength and corrosion resistance of the steel surface.