摘要
汽车行驶3万多km后发动机曲轴发生断裂。通过宏微观观察、金相检查、力学性能测试、R尺寸及表面粗糙度测量,对曲轴的断裂性质和原因进行分析。结果显示:曲轴断裂性质为疲劳断裂;曲轴基体组织为珠光体+连续网状铁素体,铁素体呈连续网状沿晶分布,导致材料塑性、冲击韧性和疲劳性能降低,是导致曲轴疲劳断裂的主要原因;此外,R角处表面粗糙度超出技术要求,促进了疲劳裂纹的萌生。
The engine crankshaft of a car fractured after running for more than 30 thousand kilometers. In order to find out the failure mode and cause,macro and micro observation,microstructure examination,mechanical properties testing and the size and surface roughness testing of the R transition region were carried out. The results show that the fracture mode of the crankshaft is failure fracture. The microstructure is made up of pearlite and ferrite network. Ferrite network reduced the ductility,impact toughness and fatigue property of the crankshaft,which is the main reason for the fatigue fracture of the crankshaft. In addition,the surface roughness of the R transition region is higher than requirement,promoting the initiation of the crack.
出处
《失效分析与预防》
2016年第4期261-264,共4页
Failure Analysis and Prevention
