What are the heat treatment methods for gear processing?
What are the heat treatment methods for gear processing?
The heat treatment of general parts (including gears) includes preliminary heat treatment and final heat treatment. The preliminary heat treatment has annealing and normalizing; the final heat treatment has quenching and tempering.
Method annealing (furnace cooling), normalizing (air cooling)
Purpose: To obtain pearlite tissue
Effect and effect:
1. Adjust the hardness to facilitate cutting;
2. Improve the organization, uniform organization, composition, elimination of reticulated carbides, etc.;
3. Refine the grains to prepare for the final heat treatment.
Method: quenching and tempering
Purpose: To obtain the corresponding M, M', T', S' organization
Effect and effect:
1. Quenching to obtain M structure, improve strength and hardness;
2. Low temperature tempering, get M' tissue, eliminate stress, and retain high hardness;
3. Tempering at medium temperature, obtaining T' tissue, and obtaining high elastic limit;
4. High temperature tempering, get S' tissue, good comprehensive mechanical properties.
Difference and connection
Annealing: annealing furnace to obtain pearlite
Normalizing: normalizing air and cooling, getting fine pearlite (S)
Quenching: quenching and quenching (through water, oil) to obtain M-type organization
Table hard and tough example
Carbon steel
Method: tempering - surface quenching - low temperature tempering
Effect: surface 50~55 HRC, heart 265~280 HB
Low-carbon steel
Method: Carburizing - quenching - low temperature tempering
Effect: surface 56~62 HRC, heart 156~179 HBS38CrMoAl
Method: tempering - nitriding
Effect: surface >700 HV, heart 26~33 HRC