1. Institute of Special Steels, Central Iron and Steel Research Institute, Beijing 100081, China
2. Research Institute, Jiangyin Xingcheng Special Steel Works Co., Ltd., Jiangyin 214429, China
3. NCS Testing Technology Co., Ltd., Beijing 100081, China
As the core part of gearbox, the performance of all gears in gearbox should be stable and consistent to avoid damage to the entire gearbox due to premature failure of individual gears. The key to the manufacturing of quality stability gears is the supply of high-quality stability gear steel materials. In this paper, the Mn-Cr automotive gear steels more than 100 heats are taken as the research object. Through the statistics and analysis of the smelting composition, C fluctuation of rolled bar, hardenability and banded structure, the research on the advanced quality stability control level and technology of domestic Mn-Cr automotive gear steel is completed. The results show that through the optimization of process parameters, the C deviation of smelting end is stably controlled ≤±0.01%, the Mn and Cr deviation are stably controlled ≤±0.05% and the proportion of C fluctuation ≤0.02% of rolled bar cross section is controlled over 95% for Mn-Cr automotive gear steel. Also, the hardenability bandwidth can be controlled ≤4HRC and the banded structure can be controlled ≤2.0 stably. According to the mass production and practice, domestic Mn-Cr gear steel has achieved high performance and high-quality stability, which will be beneficial to accelerating the development and application of advanced transmissions in China.