Mining machinery, transportation machinery and other low-speed heavy-duty gear, require the use of high reliability carburized hardened gear after grinding. Generally, the material of this kind of gear is 20grni2moa alloy carburized steel. Most factories use the traditional carburizing quenching heat treatment process: 920 ℃ carburizing × 8 h oil cooling + 650 ℃ × 3 h tempering + 820 ℃ quenching × 6 H + 180 ℃ x 2 h tempering. This process has long production cycle, large power consumption and high cost.

Through the research and test on the new carburizing quenching heat treatment of the material, and according to the performance test results, a suitable new heat treatment process is determined. The new heat treatment process can ensure reliable work, short production cycle, low power consumption and low cost.

The new carburizing and quenching heat treatment process of 20grni2moa steel has been tested for many times, the theoretical analysis and metallographic examination have been carried out. The results show that the performance index of low speed and heavy load gear has been met, the production cycle has been shortened, the labor intensity of workers has been reduced, and the energy has been greatly saved.