船用柴油机曲轴连杆断裂原因  

Fracture reasons of crankshaft connecting rod of marine diesel engine

作　　者：孙明正[1] SUN Mingzheng(Shanghai Key Laboratory of Engineering Materials Application and Evaluation,Shanghai Research Institute of Materials Co.,Ltd.,Shanghai 200437,China)

机构地区：[1]上海材料研究所有限公司、上海市工程材料应用与评价重点实验室,上海200437

出　　处：《理化检验（物理分册）》2023年第5期52-54,共3页Physical Testing and Chemical Analysis(Part A:Physical Testing)

摘　　要：某船用柴油机运行约1000 h后其曲轴连杆发生断裂。采用宏观观察、化学成分分析、力学性能测试、粗糙度检测、金相检验等方法,对该连杆的断裂原因进行分析。结果表明:该连杆的断裂性质为疲劳断裂,裂纹起源于过渡圆弧段,引起断裂的主要原因为过渡圆弧段处加工粗糙度较差,且局部曲率偏大,导致该处应力集中程度增大,从而引起疲劳裂纹的萌生和扩展,最终使连杆发生断裂。The crankshaft connecting rod of a marine diesel engine broke after running for 1000 h.The fracture reasons of the connecting rod were analyzed by means of macroscopic observation,chemical composition analysis,mechanical property test,roughness test and metallographic examination.The results show that the fracture property of the connecting rod was fatigue fracture,and the crack originated from the transition arc segment.The main reasons for the fracture was that the processing roughness at the transition arc segment was poor,and the local curvature was too large,which led to the increase of stress concentration at the point,thus causing the initiation and propagation of fatigue crack,and finally causing the connecting rod to fracture.

关 键 词：42CrMo4钢 曲轴连杆 疲劳断裂 过渡圆弧段 加工刀痕 

分 类 号：TB31[一般工业技术—材料科学与工程]