Carburizing heat treatment process

Carburizing heat treatment is not commonly used

1) reduce the temperature to the quenching temperature after carburizing, and quench directly after the heat preservation. This method is easy to make the material grain coarse, brittleness larger, the workpiece organization stress is large, can only bear the small modulus gear with less strength.

2) after carburizing, air cooling directly out of the oven or after the furnace into the slow cooling pit to cool to room temperature, and then re-enter the furnace to heat quenching. The characteristics of 20CrMnMo steel should have strict requirements on the cooling speed after the carburizing of the workpiece, otherwise the surface structure and sub-surface structure of the workpiece during cooling are not synchronized, resulting in a large tensile stress on the surface of the workpiece, the workpiece is easy to crack.

3) for the deep carburized parts with high performance requirements, in order to ensure the surface carburized layer and the quality index of the core tissue, two quenching can also be used, the first heating to the core AC3+(30-50)℃ quenching, the second heating to the surface AC1+(30-50)℃ quenching, but the heat treatment after the production of stress, and high energy consumption.

Carburizing heat treatment process

After carburizing, the furnace is cooled to 550℃ for air cooling, and then re-entered the furnace for heating and quenching. This method is the most commonly used process in the production of 20CrMnMo steel parts. There are also problems: heat treatment time is long, on the one hand, due to carburizing after the furnace cold to a certain temperature to come out, the lower the temperature of the workpiece to reduce the surface of oxidation decarburization more favorable. On the other hand, due to the workpiece quenching heating, after a period of time to establish the furnace gas carbon potential, to ensure the surface quality of the workpiece after quenching.