【作者】 陈康敏； 罗新民； 罗启富；

【Author】 CHEN Kang-min,LUO Xin-min,LUO Qi-fu (School of Material Science and Engineering,Jiangsu University,Zhenjiang 212013,China)

【机构】 江苏大学材料科学与工程学院；

【摘要】 针对某高速柴油机上中碳铬锰合金钢连杆螺栓的异常早期断裂问题,检测了螺栓材料的成分、螺栓的硬度和抗拉强度,应用热场发射扫描电镜和能谱仪等手段分析了断裂部位的形貌、微观组织和成分,采用金相分析方法检测了螺纹剖面。结果表明:连杆螺栓的断裂属严重的早期疲劳断裂,是由于螺栓在淬火和回火后的螺纹搓丝加工中,在螺纹侧面和根部产生了表面微裂纹,进而扩展并最终导致了断裂。更多还原

【Abstract】 In view of a case of unusual early break down of the connect-rod bolt made of a medium carbon Cr-Mn alloyed steel on a kind of high speed diesel engine,the chemical composition of the bolt material,and the hardness and the tensile strength of the life bolt were examined,the morphology,the microstructure and the microzone chemical composition of the fracture were analyzed by means of thermo-field emission scanning electron microscope and the energy dispersion spectrum analysis respectively.The longitudinal section of the bolt-thread part was checked by the metallography method.The results indicated that,the break down of the connect-rod bolt belongs to a serious early fatigue failure,which is caused by the manufacturing defect,the micro-cracks on the surface of the side and the root of the bolt-thread formed during the thread-making by twisting on the hardened and tempered steel.更多还原