Continuous cooling transformation and microstructure control of a Mn-Cr-V-S bainitic non-quenched and tempered steel

doi:10.13251/j.issn.0254-6051.2023.09.032

Abstract

Abstract: Continuous cooling transformation behavior of a Mn-Cr-V-S bainitic non-quenched and tempered steel was studied by using Gleeble-3800 thermal simulation test machine. The effect of cooling rate on the continuous cooling transformation curves, microstructure and micro-hardness of the steel was analyzed. In addition, the step-cooling process was set up to control microstructure for the tested steel. The results show that ferrite+pearlite, ferrite+pearlite+bainite, ferrite+bainite, ferrite+bainite+martensite, and ferrite+martensite transformations occur successively in the Mn-Cr-V-S bainitic non-quenched and tempered steel with the increase of cooling rate. When the cooling rate is 1 ℃/s, the area fraction of bainite in the tested steel is the highest and reaches 68%, and the microstructure uniformity is preferable. When the cooling rate is higher than 1.5 ℃/s, the martensite begins to appear in the steel. In order to reduce the content of ferrite and increase the content of bainite, the step-cooling process is adopted. When the cooling process is final rolling cooled to 550 ℃ at 5 ℃/s, followed by 1 ℃/s to room temperature, the uniformity of microstructure of the tested steel is the best, and the content of bainite can reach 86.8%.

Key words: bainitic non-quenched and tempered steel, continuous cooling transformation, microstructure, properties

CLC Number:

TG142.1

Wang Zhilin, Gao Xing, Jiang Bo, Wang Leiying, Zhao Haidong, Wu Han. Continuous cooling transformation and microstructure control of a Mn-Cr-V-S bainitic non-quenched and tempered steel[J]. Heat Treatment of Metals, 2023, 48(9): 191-196.

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