Influence of Heat Treatment on Properties of 35CrMo4 Steel

The heat treatment process of 35CrMo4 steel usually includes the following steps:

1. Solution annealing: heating to 800-850°C, holding time depends on material thickness and specifications, generally 1 hour/25mm. The cooling method is air cooling or directional quenching.

2. Quenching and tempering treatment: heating to 500-550°C, the holding time depends on the material thickness and specifications, generally 2 hours/25mm. The cooling method is water quenching or oil quenching.

3. Finally, tempering treatment: heating to 500-650°C, holding time depends on material thickness and specifications, generally 2 hours/25mm, and then air cooling to room temperature.

35CrMo4 steel can significantly change its properties after heat treatment. Common heat treatment methods include normalizing, quenching and tempering.

Normalizing can increase the hardness and strength of 35CrMo4 steel, but it will reduce the toughness and plasticity.

Quenching can further increase the hardness and strength of 35CrMo4 steel, but it will further reduce the toughness and plasticity. It should be noted that quenching must be carried out in an appropriate temperature range, otherwise it may cause defects such as uneven structure and cracks.

Tempering is a heat treatment to improve the toughness and plasticity of 35CrMo4 steel. This process slightly reduces the hardness and strength of the steel, but is useful for applications that require high toughness and ductility.

In conclusion, different types of heat treatment can have a significant impact on the properties of 35CrMo4 steel, and the appropriate heat treatment method should be selected according to specific needs.