Austempering

After the workpiece is quenched and heated, if it is kept at the temperature of the lower bainite transformation zone for a long time, it can complete the isothermal transformation of austenite and obtain the lower bainite structure. This kind of quenching is called austempering.

Austempering

After heating the steel to austenitize and homogenize it, quickly cool it to the bainite transformation temperature range (260～400℃), and put it in a nitrate bath or alkali bath with a temperature slightly higher than the Ms point. Keep isothermal for a certain period of time (generally, the holding time in the bath is 30~60min) to transform the austenite into bainite, and then take out the quenching process of cooling in the air.

Process purpose

① Obtain lower bainite to enhance the strength, hardness, toughness, wear resistance and plasticity of steel.

② Austempering has less deformation, higher hardness and good toughness.

③ Generally, there is no need to temper after austempering.

The main steps of the austempering process:

The first step: austenitizing treatment;

The second step: cooling treatment after austenitization;

The third step: bainite isothermal treatment;

The main applications of austempering:

Austempering is generally used for steel above medium carbon, and austempering is generally not used for low carbon steel;

②. Austempering is suitable for smaller size workpieces;

③. Austempering is suitable for processing tools with complex shapes and high dimensional accuracy requirements and important machine parts, such as molds, knives, gears, etc.

④. Austempering is suitable for workpieces with complex shapes, small deformations, and plasticity and toughness with high hardness and toughness after treatment.

⑤ Commonly used in alloy steel, high carbon steel small size parts and ductile iron parts.