Isothermal transformation and continuous cooling transformation behavior of GCr15 steel

doi:10.13251/j.issn.0254-6051.2025.05.008

Abstract

Abstract: Isothermal and continuous cooling transformation tests of pearlite in GCr15 bearing steel were carried out by using a dynamic phase transformation instrument. The TTT curve was plotted, the lamellar spacing of pearlite was measured, and the critical cooling rate for the complete transformation of pearlite was calculated. The results show that the nose temperature of the TTT curve for the isothermal pearlite transformation of deformed austenite in the GCr15 steel is 625 ℃, with incubation period of 7 s and complete transformation time of 190 s at this temperature. The lower the isothermal temperature is, the smaller the lamellar spacing of pearlite in the GCr15 steel is. The lamellar spacing of pearlite calculated by using the bulk diffusion mechanism and relevant parameters with the Thermo-calc software is in good agreement with the experimental results. It is calculated that when the isothermal temperature is lower than 680 ℃, the lamellar spacing of pearlite is less than 100 nm. The volume fraction of pearlite transformation in the GCr15 steel decreases with the increase of cooling rate. The volume fraction of pearlite transformation during the continuous cooling process calculated by Umemoto prediction model is in good agreement with the experimental results, and the critical cooling rate for the complete pearlite transformation is deduced to be 1.68 ℃/s.

Key words: GCr15 steel, continuous cooling transformation, isothermal treatment, pearlite, prediction model

CLC Number:

TG161

Zhao Xiaoyu, Huang Weibo, Lu Wenjia, Du Zunling, Zhu Lisha. Isothermal transformation and continuous cooling transformation behavior of GCr15 steel[J]. Heat Treatment of Metals, 2025, 50(5): 46-50.

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