金属热处理 ›› 2023, Vol. 48 ›› Issue (2): 308-313.DOI: 10.13251/j.issn.0254-6051.2023.02.048

• 测试与分析 • 上一篇    

发动机缸盖螺栓疲劳断裂失效分析

陈继林1,2, 张育明2, 孟一2, 闫聪2, 林鹏3   

  1. 1.钢铁研究总院有限公司 冶金工艺研究所, 北京 100081;
    2.邢台钢铁有限责任公司, 河北 邢台 054027;
    3.河北机电职业技术学院, 河北 邢台 054000
  • 收稿日期:2022-09-06 修回日期:2023-01-07 出版日期:2023-02-25 发布日期:2023-03-22
  • 作者简介:陈继林(1986—),男,高级工程师,博士,主要研究方向为先进特殊钢线材的研发,E-mail:chenjl@xtsteel.com

Failure analysis of fatigue fracture of engine cylinder head bolts

Chen Jilin1,2, Zhang Yuming2, Meng Yi2, Yan Cong2, Lin Peng3   

  1. 1. Metallurgical Technology Institute, Central Iron and Steel Research Institute Co., Ltd., Beijing 100081, China;
    2. Xingtai Iron and Steel Co., Ltd., Xingtai Hebei 054027, China;
    3. Hebei Institute of Mechanical and Electrical Technology, Xingtai Hebei 054000, China
  • Received:2022-09-06 Revised:2023-01-07 Online:2023-02-25 Published:2023-03-22

摘要: 通过断口(宏观)形貌分析、微观组织分析、化学成分检测以及硬度测试等手段对SCM435钢发动机缸盖螺栓的疲劳断裂进行失效分析。结果表明,失效SCM435钢缸盖螺栓的化学成分和显微组织合格,硬度符合技术要求。失效样件1的断裂原因为表面脱碳引起的脆性断裂,螺栓断裂部位的表面脱碳层宽为120 μm;失效样件2主要是非金属夹杂物所引起的疲劳断裂,近球状的CaS-CaO-Al2O3-MgO复合型冶金夹杂物造成了沿晶裂纹。对材料的塑韧性、表面脱碳及非金属夹杂物等指标,提出了改善建议。

关键词: 发动机, 缸盖螺栓, 疲劳断裂, 断口分析, 微观组织

Abstract: Failure analysis of fatigue fracture of SCM435 steel engine cylinder head bolts was carried out by means of fracture (macroscopic) analysis, microstructure analysis, chemical composition detection and hardness test. The results show that the chemical composition and microstructure of the failed SCM435 steel cylinder head bolts are qualified, and the hardness meets the technical requirement. The brittle fracture of the failed specimen 1 is caused by surface decarburization, the width of surface decarburization layer at the fractured part of the bolt is 120 μm. The fracture of the failed specimen 2 is mainly fatigue fracture caused by nonmetallic inclusions, and the near spherical CaS-CaO-Al2O3-MgO composite metallurgical inclusions cause intergranular crack. Suggestions for improving the indicators such as plasticity and toughness, surface decarburization and nonmetallic inclusions of the material are put forward.

Key words: engine, cylinder head bolt, fatigue fracture, fracture analysis, microstructure

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