Effect of ultrafine grain ferrite bimodal structure on mechanical properties of medium carbon steel

doi:10.13251/j.issn.0254-6051.2023.05.009

Abstract

Abstract: A medium carbon steel with 0.49%C was quenched at different temperatures in two-phase zone, then cold rolled 50% and annealed to obtain the ferritic bimodal structure. The microstructure was characterized by means of scanning electron microscope (SEM) and electron backscattered diffraction(EBSD), and the effect of the bimodal structure on mechanical properties was analyzed by tensile experiments at room temperature. The results show that the average grain size of the ferrite decreases with the increase of the quenching temperature in the two-phase zone. The strength of the tested steel is the highest when quenched at 770 ℃, the elongation is the highest at 750 ℃, and the product of strength and elongation is the highest at 760 ℃. When the proportion of submicron grains is 31.4% and the peak grain sizes of coarse grains and fine grains are respectively 2.51 and 0.79 μm, the tested steel has better matching of strength and elongation.

Key words: ultrafine grain ferrite, medium carbon steel, bimodal structure, mechanical properties, product of strength and elongation

CLC Number:

TG156.1

Zhang Jiahao, Li Hongbin, Zhao Zhihao, Xu Haiwei, Han Yun, Tian Yaqiang, Chen Liansheng. Effect of ultrafine grain ferrite bimodal structure on mechanical properties of medium carbon steel[J]. Heat Treatment of Metals, 2023, 48(5): 54-59.

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