转轴裂纹失效分析  

Failure analysis of cracks in rotating shaft

作　　者：张斌[1] 胡小华[1] 向业 

机构地区：[1]中国人民解放军驻三二〇厂军事代表室,江西南昌330024

出　　处：《金属制品》2017年第1期55-59,共5页Metal Products

摘　　要：转轴零件在磁粉探伤时发现存在裂纹,为查找裂纹产生原因,对转轴进行外观检查、断口微宏观观察、镀层厚度检测、能谱检测、氢含量检测、硬度检测。裂纹断面呈金黄氧化色或黑金色,开裂处或附近区域基体表层与心部组织均为回火马氏体,未见烧伤等异常组织,基体表层的氢质量分数略高于内壁,基体表面硬度和心部硬度相当,裂纹断面含有较多氧元素。结果表明,裂纹断口为沿晶+准解理的混合断裂特征,裂纹性质为脆性开裂,裂纹产生于电镀铬之后,主要与镀铬层非正常磨削和磨削后未及时去应力回火有关。The cracks were found by magnetic powder inspection in the rotating shaft. According to the visual examination,the macro and micro observation in the fracture,the thickness inspecting of coating,energy spectrum analysis,hardness testing and the measurement of hydrogen content,the cause of the cracks formation were determined. The crack section presents a golden oxidation colour or ocher colour,surface and lining microstructure of cracking or the area near the substrate are temperd martensite,no seen burns and other abnormal structure,hydrogen volume fraction of substrate surface is slightly higher than that of the lining,the substrate surface hardness is same of the core hardness,crack section contained more oxygen. The results show that the fracture of shaft appears the mixture of intergranular and quasi-cleavage profile,the cracks of the shaft is caused by the brittle cracking after chromium electroplating,which are related to the non-normal grinding of chromium coating and no timely distressing tempering.

关 键 词：转轴 磁粉探伤 回火马氏体 去应力回火 电镀 

分 类 号：TH13[机械工程—机械制造及自动化]