导向臂疲劳寿命试验断裂原因

Cause of fracture in fatigue life test of guiding arm

在对某导向臂进行疲劳寿命试验时,其发生早期断裂问题。采用宏观观察、化学成分分析、金相检验、硬度测试、扫描电镜分析等方法对导向臂断裂原因进行分析。结果表明:导向臂发生了低周疲劳断裂,裂纹源区位于导向臂下表面,呈多源、线源特征,源区未见冶金缺陷与加工损伤;导向臂表面存在脱碳层,脱碳层硬度偏低、抗疲劳能力下降是导向臂发生早期疲劳断裂的主要原因;导向臂表面未形成有效的喷丸强化层,导致其疲劳强度降低,促进了导向臂发生断裂。

During the fatigue life test of a certain guiding arm,early fracture occurred.The reasons for the fracture of the guide arm were analyzed using macroscopic observation,chemical composition analysis,metallographic examination,hardness testing,scanning electron microscopy analysis.The results show that the guiding arm experienced low cycle fatigue fracture,with the source region located on the lower surface of the guiding arm,exhibiting multi-source and line source characteristics.No metallurgical defects or processing damage were found in the source region.There was a decarburization layer on the surface of the guide arm,and the low hardness and reduced fatigue resistance of the decarburization layer were the main reasons for the early fatigue fracture of the guide arm.The surface of the guiding arm did not form an effective shot peening layer,resulting in a decrease in its fatigue strength,which promoted the fracture of the guiding arm.