Isothermal quenching phase transformation characteristics and mechanical properties of 300M steel

doi:10.13251/j.issn.0254-6051.2025.01.027

Abstract

Abstract: Effect of isothermal quenching process at 240-320 ℃ near Ms on the phase transformation characteristics and mechanical properties of 300M steel was studied by means of thermal dilatometer, color metallography, scanning electron microscopy and transmission electron microscopy. The results show that the isothermal quenching below Ms result in athermal martensite produces first and the incubation period of bainite transformation shortened of the 300M steel. Compared with the isothermal quenching process at 320 ℃ above Ms, the isothermal quenching process at 260 ℃ below Ms makes the retained austenite transform from blocky M/A islands to film between bainite laths, the average width of bainite lath decreases, the tensile strength increases from 1550 MPa to 1930 MPa and the total elongation increases from 7.7% to 9.2%, showing that the strength and plasticity increase simultaneously.

Key words: 300M steel, isothermal quenching, color metallography, mechanical properties

CLC Number:

TG161

Zhao Xiaoyu, Zhang Zheng, Yang Huijun, Shi Xiaohui, Zhang Min, Qiao Junwei. Isothermal quenching phase transformation characteristics and mechanical properties of 300M steel[J]. Heat Treatment of Metals, 2025, 50(1): 173-179.

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