某SS400减震器贮油缸钢管开裂原因分析

Cracking failure analysis of a car shock absorber reservoir pipe of SS400 steel

针对减震器贮油缸在运行中出现开裂的问题,采用宏观及微观的方法对失效零件的裂纹源进行分析,结合零件的显微组织及成分分析,对减震器贮油缸的开裂原因进行了研究。结果表明:贮油缸管壁基体符合SS400钢成分要求,显微组织为珠光体+铁素体,是正常的热轧状态。贮油缸钢管裂纹起源于贮油缸管壁外表面,并且从表面向试样内部扩展;贮油缸钢管开裂位置存在电泳涂层脱离现象,且开裂处贮油缸管壁变薄。贮油缸钢管电泳涂层脱落后,裸露的SS400钢管基体在应力和腐蚀的共同作用下,逐渐被蚀损,贮油缸钢管承受载荷能力下降,最终导致贮油缸钢管开裂失效。

In order to solve the problem of cracking in the operation of a car shock absorber reservoir pipe of SS400 steel,the method of macro and micro analysis is adopted to analyze the crack source of the failed pipe.The reason for the cracking of the pipe is studied by analyzing the microstructure and composition of the shock absorber reservoir pipe,and as a result,the pipe wall steel meets the requirements of SS400 steel composition.Its microstructure is pearlite and ferrite in normal hot rolled state.Originated from external surface of the shock absorber reservoir steel pipe,the cracks gradually extended to the interior.Electrophoretic coating of steel pipe peeled off at cracking position,and the wall of the reservoir steel pipe has become thin.After the peeling-off of the coating of the shock absorber reservoir pipe,the SS400 steel pipe matrix was gradually eroded under the combined action of stress and corrosion,and as a result,the load capacity of the steel pipe decreased.Finally,stress corrosion results in cracking of the shock absorber SS400 steel pipe.