Transactions of Materials and Heat Treatment

Title：Analysis on expansion fracture defects for 36MnVS4 non-tempered steel expansion fracture connecting rod

Authors： Qu Xiaobo1 An Jinmin1 Zhang Yongqi2 Mu Tianzhu3 Zhang Chaolei2

Unit： (1.Jiangsu Yonggang Group Co. Ltd. Zhangjiagang 215628 China 2.Institute for Carbon Neutrality University of Science and Technology Beijing Beijing 100083 China 3.Zhangjiagang Huanxin Precision Forging Co. Ltd. Zhangjiagang 215621 China)

KeyWords： 36MnVS4 non-tempered steel expansion fracture connecting rod drop-dregs thermo mechanical control process percentage reduction of area

ClassificationCode：TG142.1

year,vol(issue):pagenumber：2024,49(9):239-245

Abstract：

The expansion fracture defects of uneven fracture and drop-dregs for 36MnVS4 non-tempered steel expansion fracture connecting rods were analyzed. Then, the quantitative analysis of microstructure, the observation of fracture morphology and the mechanical property test were conducted, and the standards of VW 50030 and T/CCMI 13.1—2021 were compared. The results show that the microstructure of 36MnVS4 expansion fracture connecting rod is ferrite and pearlite, but the ferrite content on drop-dregs side of the defective connecting rods is 37.0%-39.8%, which does not meet the standard requirements. The percentage reduction of area of the defective connecting rod is 51.0%-51.5%, which exceeds the standard requirement of 30%-50%. At the same time, there are obvious ductile fracture areas in the drop-dregs area, which proves that there is plastic deformation in the expansion fracture process. Thus, the excessive ferrite content in the organization and the large percentage reduction of area result in the poor expansion fracture performance of expansion fracture connecting rod, which is the main reason for the occurrence of expansion fracture defects.

Funds：

基金项目:张家港市科技计划项目（202303）

作者简介：屈小波（1983-），男，本科，高级工程师 E-mail：qubo6101@163.com 通信作者：张朝磊（1984-），男，博士，副教授 E-mail：zhangchaolei@ustb.edu.cn

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