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.

Preliminary Heat Treatment

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.

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