Austenitization kinetic characteristics and microstructure evolution of as-cast GCr15 steel during continuous heating

doi:10.13251/j.issn.0254-6051.2021.11.003

Abstract

Abstract: Linear expansion of the as-cast GCr15 steel with different heating rates (0.5, 3, 5, 30, 100 ℃/s) was recorded using DIL805A thermal dilatometer, and their respective thermal expansion curves and austenite volume transformation fraction curves were obtained. The effect of heating rate on austenitization of the as-cast GCr15 steel was studied. The austenite transformation process of the steel during continuous heating was observed and analyzed by means of a high temperature metallurgical microscope. The results show that austenite transformation of the GC15 steel during continuous heating can be divided into three stages: the transformation of pearlite to austenite (760-790 ℃), the dissolution of (Fe, Cr)₃C_II into austenite (790-890 ℃) and the austenite homogenization (>890 ℃). And as the heating rate increases, the critical temperature of phase transition increases, and the rate of phase transition increases. During the continuous heating process, the austenitic transformation of the as-cast GCr15 steel is an alternate process of nucleation and growth.

Key words: as-cast GCr15 steel, thermal expansion curve, transition rate, austenitization, high temperature metallurgical microscope

CLC Number:

TG142

Zhou Denghu, Hou Qingyu, Han Weixue, Jiang Yan, Huang Zhenyi. Austenitization kinetic characteristics and microstructure evolution of as-cast GCr15 steel during continuous heating[J]. Heat Treatment of Metals, 2021, 46(11): 17-23.

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