Transactions of Materials and Heat Treatment

Title：Influence of differential cooling control on microalloy carbonitride precipitated phase for bulging fractured connecting rod of C70S6 steel

Authors： Wang Zhanhua1 Hui Weijun2 Zhao Xiuming3 Cheng Long4

Unit： 1. School of Mechanical and Electronic Technology Suzhou Institute of Trade & Commerce 2. School of Mechanical Electronic and Control Engineering Beijing Jiaotong University 3. School of Materials Science and Engineering Nanjing Institute of Technology 4. Zhejiang Asia Pacific Mechanical and Electrical Co. Ltd.

KeyWords： C70S6 non-quenched and tempered steel cooling speed bulging fractured connecting rod precipitated phase precipitation strength

ClassificationCode：TG142.1

year,vol(issue):pagenumber：2023,48(3):27-33

Abstract：

In order to promote the localization process of non-quenched and tempered steel C70S6 and clarify the problem of cooling speed process control during the production of C70S6 steel bulging fractured connecting rod, the influence of cooling speed on the precipitation of microalloy carbonitride in C70S6 steel was analyzed and discussed. Then, through the use of metallographic microscope (OM), scanning electron microscope (SEM) and X-ray diffractometer (XRD) and other equipments, using physical-chemical phase analysis method, the microscopic characteristics such as composition and particle size distribution of the microalloy carbonitride precipitated phase in the I-beam position of domestic C70S6 non-quenched and tempered steel bulging fractured connecting rod by air cooling and wind cooling phase after hot forging were observed, and the precipitation strength behavior of microalloy carbonitride M(CN) precipitated phase was quantified. The results show that when the cooling speed is 3 and 4 ℃·s-1, the microalloy carbonitride precipitated phase are all face-centered cubic structures, and the nominal chemical formulas are (V0.896Cr0.070Mo0.034)(C0.259N0.741) and (V0.927Cr0.050Mo0.024)(C0.259N0.740). The size distribution of the precipitated phase is concentrated in 1-18 nm, and the contributions of precipitated phase to yield strength are about 122.0 and 127.6 MPa, respectively. When the cooling speed is accelerated, and the size of microalloy carbonitride precipitated phase is refined to a certain extent, but the effect is not obvious.

Funds：

国家重点研发计划项目(2016YFB0300100)；苏州经贸职业技术学院2022年校级课题(YJ-ZX2208)

作者简介：王占花(1989-)，女，博士，讲师 E-mail：16116344@bjtu.edu.cn

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