发动机38CrMoAlA离合器齿轮缺陷分析

发动机38CrMoAlA离合器齿轮在工厂试车后，磁粉检测发现靠近齿轮端面的杆部有3条磁痕缺陷。通过对齿轮上的磁痕缺陷进行外观检查、电镜观察、金相检查、化学成分分析和断口观察，并抽取了1件新品齿轮进行了故障模拟再现，确定了磁痕缺陷的性质及产生原因，并采取了有效措施。结果表明：磁痕显示的原因与该位置存在裂纹有关；由于离合器齿轮在机加磨削过程中存在较大的残余应力，在试车工作应力的诱发下，导致了一次性裂纹的产生。通过改进加工工艺和低温退火工艺可解决该故障问题，对于以后齿轮故障问题的解决和处理有一定的借鉴和指导作用。

Defect Analysis of 38CrMoAlA Clutch Gear of Engine

A 38CrMoAIA clutch gear of engine was found to have 3 magnetic mark defect display at the rod near the end surface by magnetic particle inspection after testing. In order to find out the failure mode and cause, micro and macro observation, microstructure examination, and chemical composition analysis were performed, and simulation testing were carried out with a new gear. The results show that magnetic mark defect display was due to the cracks there. The cracks initiated under the co-effect of residual stress induced during grinding process and the working stress during testing. The failure can be prevented by improving machining process and adopting low-temperature tempering.