金属热处理 ›› 2020, Vol. 45 ›› Issue (4): 224-228.DOI: 10.13251/j.issn.0254-6051.2020.04.047

• 测试与分析 • 上一篇    下一篇

42CrMo钢曲轴连杆颈磁痕显示的成因分析

黄斌1, 林升垚1, 毛晓峰1, 李亮群1, 郑奇峰1, 顾剑锋2, 刘庆冬2   

  1. 1. 桂林福达股份有限公司, 广西 桂林 541199;
    2. 上海交通大学 材料科学与工程学院, 上海 200240
  • 收稿日期:2019-09-22 出版日期:2020-04-25 发布日期:2020-05-08
  • 通讯作者: 刘庆冬,助理研究员,E-mail:qdliu@sjtu.edu.cn
  • 作者简介:黄 斌(1966—),男,高级工程师,主要从事金属材料成型、加工及热处理等,E-mail:huangbin@glfoto.cn
  • 基金资助:
    上海交通大学青年人才科研能力培育专项(19X100040016)

Cause analysis of magnetic particle indication on 42CrMo steel crankshaft neck

Huang Bin1, Lin Shengyao1, Mao Xiaofeng1, Li Liangqun1, Zheng Qifeng1, Gu Jianfeng2, Liu Qingdong2   

  1. 1. Guilin Fuda Co., Ltd., Guilin Guangxi 541199, China;
    2. School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
  • Received:2019-09-22 Online:2020-04-25 Published:2020-05-08

摘要: 利用磁粉探伤对42CrMo钢曲轴锻件的连杆颈部位进行检测,发现明显的类似发纹的磁痕显示。通过OM、SEM形貌观察和EDS成分分析发现,连杆颈表层部位基体的显微组织不均匀,出现明显的成分偏析带,宽度约20~50 μm,C、Mn、S、Al、Cr元素含量相对基体较高,并含有少量的MnS夹杂。42CrMo钢棒状原料的中心偏析在模锻时沿着金属流动方向发生转动,偏析流线“遗传”至终态连杆颈表层而造成显微组织和化学成分的不均匀,进而导致磁导率的差异而出现磁痕显示。锻后的调质处理和表面感应淬火在一定程度上可以改善但不能消除这种宏观成分偏析。

关键词: 42CrMo钢, 曲轴锻件, 磁粉探伤, 成分偏析

Abstract: The hair-line magnetic particle indication was detected by magnetic particle testing at the neck part of 42CrMo steel crankshaft. The microstructure just below the magnetic particle indication was studied by OM,SEM and EDS. The results show that the microstructure is considerably uneven,and significant segregation bands are found with a width of about 20-50 μm and enriched with the C, Mn, S, Al and Cr elements. In addition, individual MnS inclusion is also detected. The segregation bands paralleling with the axis of columnar 42CrMo steel are rotated during die forging process, especially at the neck part of 42CrMo steel crankshaft with severe plastic distortion.The macro-segregation is inherited to the final crankshaft product. The heterogeneous compositional distribution leads to the difference of magnetic permeability and thus the appearance of magnetic particle indication. The forging process and the following quenching-tempering as well as surface induction quenching treatment can mitigate to some extent but cannot totally eliminate the segregation.

Key words: 42CrMo steel, crankshaft, magnetic particle testing, segregation

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