S375型乳化液泵曲轴断裂失效分析

Failure analysis on fractured crankshaft of S375 emulsion pump

针对某矿S375型乳化液泵曲轴断裂的问题,对曲轴硬度、化学成分和金相组织等进行了失效分析,并应用有限元技术,对曲轴在最大工作载荷下的受力进行了分析。结果表明,曲拐表面进行过渗氮处理,渗氮层厚0.65 mm,表层硬度为400 HV,比心部母材的硬度高1倍左右,曲拐与曲肩的圆角处无渗氮层,而曲轴的疲劳源正位于此位置。有限元分析结果显示,曲轴的最大应力为65 MPa,应力集中在曲轴断裂的曲拐圆角处,与实际情况相吻合。结合曲轴试验和有限元的综合分析结果,对曲轴结构、材料和工艺等方面提出了改进意见。

In view of facture of the crankshaft of S375 emulsion pump in a mine, the paper conducted failure analysis on the hardness, chemical composition and metallography of the crankshaft, and applied finite element method to analyze the force state of the crankshaft in maximum loading mode. The results showed: a nitrided layer was formed on the surface of the crank and the depth of the nitrided layer was about 0.65 mm; the hardness of nitrided surface of the crank was about 400 HV, which was one time larger than the hardnessof the materials in the centre of the crank; there was no nitrided layer found on the fillet between the crank and shoulder, from which the fatigue of the crankshaft initiated. The FEA results revealed that the maximum stress of the crankshaft was 65 MPa and the stress concentrated on the fillet of the crank where the crankshaft fractured, which coincided with the test results. In addition, on the basis of test results and FEA results, some suggestions were put forward to improve structure, material and manufacture process of the crank.