马仙龙1，张正华2
1.无锡康明斯涡轮增压技术有限公司，江苏 无锡 214045;2.河南交通职业技术学院，河南 郑州 450005
摘要：针对某发动机耐久试验中增压器旁通阀轴与阀片臂焊接失效问题，采用电子显微镜扫描故障旁通阀断口，发现旁通阀轴焊接熔池内有裂纹，试验验证裂纹扩展具有明显的方向性，与载荷的施力方向强相关，判定焊接失效为高温环境下的机械疲劳断裂。从焊接工艺上改善焊接质量，消除和降低应力集中，降低焊接失效风险。通过对比台架、路试试验与旁通阀轴焊接疲劳耐久加速试验的疲劳累计损伤，完成改进焊接质量样件的寿命风险评估，避免台架、路试耐久试验可能造成的时间与成本浪费。
关键词：旁通阀轴；焊接；疲劳失效
Abstract：The fatigue failure happened on the turbocharger wastegate shaft and valve welding interface in engine endurance test, it was observed the shaft and welding pool with initial micro cracks by SEM analysis. It is verified that the crack propagation has obvious directionality which is strongly related to the force direction by test. It could be inferred that the welding failure is mechanical fatigue under high temperature. The welding quality is improved by welding process optimization, and stress concentration is eliminated. The risk assessment for improved welding samples fatigue life is carried out by calculating the welding cumulative fatigue damage of engine test and road test as well as the wastegate shaft welding fatigue accelerate test. This method can reduce the cost of engine test and road test.
Keywords:wastegate shaft; welding; fatigue failure
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