42CrMo钢导向端轴的断裂原因分析

Fracture Reason Analysis of Guide Bearing of 42CrMo Steel

采用宏观检验、化学成分分析、力学性能测试、金相检验及能谱扫描的方法,对42CrMo钢导向端轴断裂的原因进行了分析。结果表明:端轴断口附近区域存在非金属夹杂物,且加工过程中的热处理制度不当,未得到理想、均匀的回火索氏体组织。淬火导致端轴边缘部位产生体积膨胀及应力集中,致使端轴在非金属夹杂物处形成微裂纹。随着裂纹的不断扩展,最终端轴断裂失效。

By means of macrographic inspection,chemical composition analysis,mechanical properties testing,metallographic examination and energy spectrum scanning,the fracture reason of guide bearing of 42 CrMo steel was analyzed.The results show that the fracture was occurred due to non-metallic inclusions and unreasonable heat treatment mechanism.The expectanted uniform tempered sorbite structure was not obtained.Quenching treatment led to volume expansion and stress concentration on the edge of guide bearing,and then microcrack formed at the position of nonmetallic inclusions,finally with the crack extending the guide bearing fractured.