40Cr钢螺栓断裂失效原因分析  

Study on Fracture Failure of 40Cr Screw Shaft

作　　者：董雪娇 杨大巍 刘锦燕[1] 刘兆华[1] 黄洁 Dong Xuejiao;Yang Dawei;Liu Jinyan;Liu Zhaohua;Huang Jie(Pangang Group Research Institute Co.Ltd,State Key Laboratory of Vanadium and Titanium Resources Comprehensive Uti-lization,Panzhihua 617000,Sichuan,China)

机构地区：[1]攀钢集团研究院有限公司,钒钛资源综合利用国家重点实验室,四川攀枝花617000

出　　处：《钢铁钒钛》2020年第3期172-176,共5页Iron Steel Vanadium Titanium

摘　　要：针对某厂水处理站服役4年便发生早期断裂失效的40Cr螺栓,采用化学成分分析、力学性能检测、扫描电镜以及光学显微镜等方法对其断裂原因进行了分析。结果表明,断裂起源于第二道螺纹根部,该处存在多道次焊接是引起疲劳断裂的诱因;轴的心部组织是珠光体+网状铁素体,属未经调质处理的原材料组织,其力学性能和疲劳强度不能满足使用要求;疲劳源处发现硬脆相马氏体组织,与轴在运转过程中不同心(偏心)产生交变应力的共同作用下使裂纹快速扩展直至断裂。The early fracture failure of 40 Cr screw shaftoccurred in a water treatment station of a factory after service for 4 years.The fracture causes were analyzed by chemical composition analysis,mechanical properties detection,scanning electron microscope and optical microscope.The results show that the fracture originates from the root of second threads,and the multi pass welding is causing fatigue fracture.The microstructure of core part of the shaft is composed of pearlite+net-like ferrite,which come from original structure without quenching and tempering treatment.Its mechanical properties and fatigue strength cannot meet the requirements.The fatigue source exists hard brittle martensite structure,which is in combination with alternating stress due to eccentric movement of shaft causing the crack to rapidly expand to fracture.

关 键 词：40CR钢 早期断裂 疲劳断裂 疲劳源 

分 类 号：TH131[机械工程—机械制造及自动化] TG115[金属学及工艺—物理冶金]