Effect of hot rolling + quenching and partitioning on microstructure and properties of Q235 steel

doi:10.13251/j.issn.0254-6051.2021.11.011

Abstract

Abstract: Effect of partitioning temperature during one-step quenching and partitioning (Q&P) process and one-step hot rolling + quenching and partitioning (HR-Q&P) process on microstructure and mechanical properties of the Q235 steel was studied by means of optical microscope (OM), scanning electron microscope (SEM), electronic universal testing machine and digital microhardness tester. The results show that the grains of the tested steel are obviously refined by HR-Q&P process, and the microstructure is composed of martensite, ferrite and bainite. When partitioned at 350 ℃ by HR-Q&P process, the yield strength and tensile strength of the steel reach the maximum, the values of which are 449 MPa and 560 MPa, respectively, while the elongation decreases by 8% compared with the as-received one, but still exceeds 30%. The hard phases of martensite and bainite appear at the same time during HR-Q&P process, resulting in secondary cracking. Under the one-step Q&P process, compared with the as-received tested steel, the tensile strength increases by about 32%, the yield strength increases by nearly one times, and the elongation remains above 26%.

Key words: Q&P process, hot rolling, Q235 steel, martensite, fracture morphology

CLC Number:

TG156.93

Meng Xiaoyue, Lin Wanming, Ning Angang, Ma Rongze, Zhang Zhiwei. Effect of hot rolling + quenching and partitioning on microstructure and properties of Q235 steel[J]. Heat Treatment of Metals, 2021, 46(11): 71-77.

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