45Mn2螺栓非正常拉伸断裂原因分析
Causes and Analysis of Non-normal Stretched Fracture of 45Mn2 Bolt
李海升, 杨 川, 高国庆, 郑 周
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作者单位：西南交通大学 材料科学与工程学院, 四川 成都 610031
中文关键字：45Mn2螺栓； 断裂； 淬火； 冷挤压
英文关键字：45Mn2 bolt; fracture; quenching; cold extrusion
中文摘要：某厂生产的45Mn2螺栓进行拉伸实验时出现非正常断裂，采用宏观断口分析、金相分析等方法对断裂螺栓进行了分析。结果表明，非正常断口的形成是螺栓在拉伸前螺纹根部就存在裂纹。螺栓根部长的裂纹是淬火中形成的，在冷挤压螺栓时螺纹根部就形成微裂纹，这些微裂纹淬火时成为根部淬火裂纹形成的关键原因。
英文摘要：The non-normal fracture appeared on 45Mn2 bolt during the tensile test was analyzed by macrofractography, metallographic analysis and so on. The results show that the non-normal fracture of the bolt is caused by generation of the crack in the root of thread before the tensile test; the long crack in the root of thread is formed by quenching, the micro-crack in the root of thread is formed in cold extrusion process and the micro-crack leads to the formation of the long crack by quenching.