针对20CrMnMoA齿轮在试运转过程中沿径向开裂的问题,对齿轮断裂件表面进行磁粉探伤、断口宏观观察、扫描电镜和金相显微分析。结果表明,齿轮断裂表面有较多的裂纹,裂纹内有硫化物夹杂,部分裂纹沿硫化物夹杂延伸,裂纹位于渗碳层区域,附近组织无异常,齿轮金相组织与技术标准要求相符合。 In view of the problem of 20CrMnMoA gear cracking along the radial direction during the trial operation, the surface of the gear fracture was inspected by magnetic particle inspection, the fracture was observed macroscopically, the scanning electron microscopy and the metallographic microscopic analysis. The results show that there are many cracks on the surface of the gear fracture, sulfide inclusions in the crack, part of the crack extending along the sulfide inclusions, the crack is located in the carburized layer area, the surrounding tissue is normal, and the microstructure of the gear is in accordance with the technical standards.