李康宁1,2，王刚1,2，陈广茂1,2，于健1,2

1.内燃机可靠性国家重点实验室, 山东潍坊261061；2.潍柴动力股份有限公司, 山东潍坊261061

摘要：采用宏观分析、扫描电镜分析、金相分析、硬度分析及仿真分析等方法，对龟裂挺柱进行失效分析，挺柱材料成分、表面硬度及渗碳层深度符合设计要求，表层及基体组织正常，挺柱底面磨削时进给量过大，导致挺柱底面及内部温度过高，在冷却时产生热应力，进而产生原始裂纹。原始裂纹在挺柱底面与凸轮轴接触运行过程中进一步扩展形成麻点及龟裂。通过对挺柱工艺进行优化，合理预留磨削量，并减小磨削速度，对磨削区进行充分冷却，新批次挺柱底面未产生裂纹，故障消除。

关键词：柴油机；挺柱；磨削裂纹；失效分析

Abstract:An investigation is made on the tappet of a generator diesel engine. The morphology of cracks, microstructure, chemical composition, hardness as well as contact stress are performed by stereomicroscope, scanning electron microscopy, optical microscopy, hardometer and finite element software, respectively. The experimental results show that the chemical composition and the hardness value of the tappet reach the technique requirement. Excessive grinding is the main cause of the original crack, and the original crack expanded during the running period, dots and cracks are generated. Optimizing the manufacturing process by reducing the grinding amount and rate, and improving cooling efficiency, the production problem of tappet is solved perfectly.

Keywords:diesel engine; tappet; grinding crack; failure analysis