Investment casting isothermal quenching

After quenching and heating process, if the investment castings maintained the temperature of lower bainite transition zone for a long time, and let the structure of the investment castings to complete the austenite transformation, the castings can get the lower bainite structure. Such hardening process is called 'Isothermal Quenching'.

Processes/steps of isothermal quenching are as below,

Step 1, Heating the castings to get the austenite structure 

Step 2, Cooling the castings to get the transformation temperature of lower bainite, about 260 ~ 400 ℃.

Step 3, Putting the castings into the nitrate salt bath and alkaline bath, and keeping certain temperature for some time, usually 30 - 60mins. Thus, to transform the austenite structure of investment castings to the lower bainite structure.

Step 4, Getting the catings out from the bath and cooling the castings in air

Advantages of isothermal quenching process

a. Achieving lower banite structure to increase the strength, hardness, toughness, wear resistant and plasticity of the castings.

b.Disformation of investment castings is lower by using isothermal quenching. Hardness of the castings is high, but the plasticity of the castings still keep good.

c.There's no need to do tempering after the isothermal quenching process.

Applicastion of Isothermal quenching

1.Isothermal quenching process are usually used for mid carbon steel or higher carbon steel. It's not suitable for low carbon steel

2.Isothermal quenching is widely used for small size castings.

3.Isothermal quenching usually applied to heat the castings with complex structure,  high accuracy requirements and the most important machine components, such as molds, toolings and gears, etc.

4.Isothermal quenching is used as heat treating process for castings with complex structure, little deformation during heating process, but with high hardness, toughness and plastcity.

5.Isothermal quenching is widely used to heat the alloy steel castings, high carbon steel with small size castings and the ductile iron castings.

6.Isothermal quenching process is widely used for heating the gears, sprockets and other similar castings.

If you have RFQs with such heat treatment requirements, please contacting us.