摘要
采用光学显微镜、扫描电镜、显微硬度计和有限元分析,对在汽车飞轮冷轧成型中失效的低碳合金渗碳钢轧辊进行断面观察、显微组织观察、硬度分布测试及基本受力分析。结果表明,失效轧辊渗碳层主要由针状回火马氏体、细小碳化物和少量残留奥氏体组成。从失效轧辊槽口表面到心部,硬度逐渐降低。失效轧辊槽口附近的显微硬度分布不均匀,渗碳层厚度低于设计要求且内部存在低硬度微区。多条微裂纹在轧辊槽口底部萌生,并汇合成主裂纹,沿着槽口底部向内扩展,其扩展方向与有限元分析基本一致。轧辊的早期失效主要与热处理工艺以及复杂的服役载荷有关。
Fracture surface observation,microstructure observation,hardness distribution test and the basic stress analysis of a low carbon alloy carburized steel roller failed in roll forming process for manufacturing automobile flywheel,were investigated by means of optical microscope,scanning electron microscope,microhardness tester and finite element analysis.The results show that the carburized layer of the failed roller is mainly composed of acicular tempered martensite,small carbides and a few retained austenite.The microhardness decreases from the roller notch surface to the core.The distribution of microhardness near the failed roll notch is not uniform,the case depth of carburizing layer is lower than the design specification and low hardness microzones are formed in the carburized layer.Microcracks initiate from the roller notch bottom,then joint into a main crack and propagate from the notch bottom surface to the inner.The propagation direction of the main crack basically agrees with the result of finite element analysis.Both the heat treatment process and the complex loads in the service environment are attributed to the early failure of the roller.
作者
吕犇
万训智
刘澄
LüBen;Wan Xunzhi;Liu Cheng(School of Mechanical Engineering,Yangzhou University,Yangzhou Jiangsu 225000,China)
出处
《金属热处理》
CAS
CSCD
北大核心
2024年第5期272-278,共7页
Heat Treatment of Metals
