Influence of Nb microalloying on grain size of austenite in hightemperature carburized gear steel
LIU Huasong,DONG Yannan,ZHENG Hongguang,LAN Peng,LIU Xiangchun,ZHANG Jiaquan
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1.School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China;2.Central Research Institute of Baoshan Iron and Steel Co., Ltd., Shanghai 201900, China
Abstract: It is an important approach to develop the highquality gear steels through Nb microalloying to increase the carburizing temperature. Based on 20Cr steel, the influence of Nb addition of 0.02%, 0.04%, 0.06% and 0.08% on the prior austenite grain after carburizing was investigated with laboratory smelting, forging and high temperature pseudocarburizing experiments in the range of 977—1134℃. On this basis, according to the thermodynamic calculation and the kinetic modeling for precipitation particle ripening, the pinning strength of AlN and Nb(C,N) particles was estimated and used for establishing the relationship with the austenite grain size. Then, the predictive model for Al and Nbcontaining gear steels to control the austenite grain size was obtained. Finally, the influence of Nb content on the carburizing temperature of 20Cr steel was analyzed based on the predictive model, and the composition suggestion for Nb microalloying was proposed for the target of hightemperature carburizing process.
LIU Huasong1,DONG Yannan1,ZHENG Hongguang2,LAN Peng1,LIU Xiangchun2,ZHANG Jiaquan1.
Influence of Nb microalloying on grain size of austenite in hightemperature carburized gear steel[J]. Journal of Iron and Steel Research, 2021, 33(8): 828-838 https://doi.org/10.13228/j.boyuan.issn1001-0963.20210106