Grain coarsening behavior during pseudo carburizing process of low-carbon gear steel 20CrMnTi for automobile

doi:10.13251/j.issn.0254-6051.2024.02.013

Abstract

Abstract: A 20CrMnTi gear steel without Nb addition was designed, and the influence and mechanism of pseudo-carburizing temperature on its prior austenite grain size were studied through grain size measurement and precipitate distribution analysis. The results show that the maximum pseudo-carburizing temperature of the designed steel is 970 ℃. The C content in (Ti, Mo)(C, N) particles is reduced, while the N content is opposite after pseudo-carburizing treatment compared with the hot-rolled steel, which confirms the redissolution and ripening of the second phase (Ti, Mo)(C, N) particles, and being more obvious when the pseudo-carburizing temperature is higher (980 ℃). Moreover, the volume fraction of the fine dispersed second phase (Ti, Mo)(C, N) particles decreases sharply when the pseudo-carburizing temperature is 980 ℃, at which the large size second phase (Ti, Mo)(C, N) particles increases, thus weakening the pinning effect on prior austenite grains and resulting in the abnormal grain growth.

Key words: 20CrMnTi gear steel, pseudo-carburizing treatment, prior austenite, precipitated particle, ripening

CLC Number:

TG142.1

Wu Wei, Yuan Qing, Mo Jiaxuan, Ren Jie, Zhang Zhicheng, Xu Guang. Grain coarsening behavior during pseudo carburizing process of low-carbon gear steel 20CrMnTi for automobile[J]. Heat Treatment of Metals, 2024, 49(2): 84-90.

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