Several Heat Treatment Processes after Carbonitriding in Well type Furnace and Their Applicable Scope

1. Direct water quenching from the eutectic temperature and low temperature tempering:

The process is simple and is one of the widely used heat treatment methods. Suitable for medium low carbon steel or low carbon low alloy steel. It is only applicable to liquid carbonitriding or well furnace carbonitriding. It is not applicable to carbonitriding of sealed box furnace or continuous operation furnace.

2. Direct oil quenching from the eutectic temperature and low temperature tempering:

The process is simple and is one of the widely used heat treatment methods. It is suitable for alloy steel quenching and direct quenching after carbonitriding in various furnaces.

3. Direct step quenching by CO infiltration temperature, air cooling and low temperature tempering:

Quenching oil can be used in the temperature range of 40~105~c. Some parts require small heat treatment deformation. High flash point can be used for quenching oil with high oil temperature, and high alloy steel parts require deformation and salt bath quenching can also be used.

4. Direct gas quenching:

For small parts, gas quenching can reduce deformation and cost, but the furnace should be carefully loaded in order to evenly cool the air flow during gas quenching.

5. One time heating and quenching:

It is applicable to direct quenching for various reasons or processing after CO infiltration. Heating before quenching shall be carried out in the furnace with good deoxidization or in the heating equipment with protective atmosphere.

6. Direct quenching from CO infiltration temperature, cold treatment:

It is applicable to alloy steels containing more Cr and Ni, such as 12CrNi3A, 20Cr2Ni4A, 18cr2i4wa-70~- 80 ℃ cold treatment, which can reduce the residual austenite and make the surface hardness meet the technical requirements.

7. Cool well or cool well in air, from penetration temperature, high temperature tempering, reheat quenching, low temperature tempering:

As mentioned above, if machining is required after CO penetration, high temperature tempering can also be used instead of cold treatment to reduce residual austenite. High temperature tempering shall be carried out in pig iron scrap or protective atmosphere.