火车制动杠杆吊座用40Cr螺栓断裂原因分析  

Failure cause analysis of 40Cr bolt used in hanger of train brake lever

作　　者：刘艳锋 刘小民 王法云 赵宇清 李晓增 潘永红 Liu Yanfeng;Liu Xiaomin;Wang Fayun;Zhao Yuqing;Li Xiaozeng;Pan Yonghong(Guangzhou Quality Supervision and Testing Institute,Guangzhou Guangdong 511447,China)

机构地区：[1]广州质量监督检测研究院,广东广州511447

出　　处：《金属热处理》2024年第1期279-283,共5页Heat Treatment of Metals

摘　　要：某火车制动杠杆吊座用40Cr螺栓在使用约2年后发生断裂。采用断口分析、化学成分分析,金相检验、硬度测试、冲击试验等方法,分析了40Cr螺栓断裂的原因。结果表明,断裂螺栓的显微组织为含有回火索氏体、上贝氏体、下贝氏体、残留奥氏体和非金属夹杂物的带状组织,螺栓的硬度和冲击性能均不满足标准要求。在火车运行过程中,紧固螺母发生了松动,长时间的振动撞击使与螺杆交接处的螺纹根部首先发生开裂,并导致了后续螺栓的沿晶脆性断裂。40Cr bolt used in hanger of train brake lever was broken after running about two years.The reasons for failure of the 40Cr bolt were analyzed through fracture analysis,chemical composition analysis,metallography detection,hardness test and impact test.The results show that the microstructure of the failed bolt is banded structure consisting of tempered sorbite,upper bainite,low bainite,retained austenite and non⁃metallic inclusion,while the hardness and impact property of the bolt do not meet the standard requirements.During the running of train,the fastening nut become loose,and the long⁃term vibration and impact make the root of the thread at junction with the screw crack first,which leads to the subsequent intergranular brittle fracture of the bolt.

关 键 词：40Cr螺栓 带状组织 脆性断裂 上贝氏体 

分 类 号：TG115[金属学及工艺—物理冶金]