Transactions of Materials and Heat Treatment

Title：Influence of grain size and carbide structure refinement on properties of 18Cr14Co12Mo4 bearing steel

Authors： Xiao Guizhi1 Li He1 Pang Yuhua1 Kong Haoran1 Liu Dong2

Unit： 1.School of Metallurgy Xi′an University of Architecture and Technology 2.School of Materials Northwest Polytechnical University

KeyWords： bearing steel two upsetting and two drawing forging ratio high-temperature diffusion grain size carbide segregation

ClassificationCode：TG316

year,vol(issue):pagenumber：2024,49(10):1-7

Abstract：

After high-temperature diffusion heat treatment, the coarse structure of 18Cr14Co12Mo4 bearing steel is not completely eliminated, and the grain size is abnormally coarse, which decreases the mechanical properties of material. For the problem, the test of two upsetting and two drawing was conducted on 18Cr14Co12Mo4 bearing steel after high-temperature diffusion heat treatment with a forging ratio of 2.0-2.2, and its microscopic properties were characterized by field emission scanning electron microscopy. Then, the influences of grain size and microstructure on the mechanical properties before and after forging were compared and analyzed. The results show that the test refines the grain size to make the average grain size be 30 μm, decreases the size of micro scale carbide and oxide, alleviates the carbide segregation caused by the uneven distribution of alloy components, increases the yield strength from 272 MPa to 340 MPa, greatly enhances the tensile strength from 381 MPa to 1637 MPa with an increasing of about 4.3 times, and improves the elongation from 13.5% to 24.2%. The refinement of grain size and carbide structure notably enhance the mechanical properties of 18Cr14Co12Mo4 bearing steel.

Funds：

国家自然科学基金资助项目（51804241）

作者简介：肖桂枝（1978-），女，博士，副教授，E-mail：guizhixiao@163.com；通信作者：庞玉华（1965-），女，博士，教授

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