CCT curves and initial corrosion properties of Q355NH steel

doi:10.13251/j.issn.0254-6051.2021.07.016

Abstract

Abstract: Through dilation curves and metallographic-hardness method, the transformation point of Q355NH low-carbon weathering steel austenitized at 840 ℃ and cooled with different cooling rates was measured, and the CCT curves were obtained. Based on this, the microstructure, mechanical properties and corrosion resistance of the steel under different cooling methods were studied. The results show that the microstructure of the Q355NH steel is composed of ferrite and pearlite when the cooling rate is in range of 0.1-10 ℃/s. As the cooling rate increases, the yield strength increases from 360 MPa (furnace cooling) to 420 MPa (wind cooling). Carbides precipitate along the grain boundary under furnace cooling methods, and the number and density of pearlite are highest under wind cooling method. Under these two cooling method, the steel has a lower corrosion potential, but the mass loss in the initial stage of the salt spray corrosion test is comparatively greater.

Key words: Q355NH steel, weathering steel, CCT curves, initial corrosion

CLC Number:

TG172

Wang Linxu, He Jinhang, Sun Bo, Bai Jie, Wang Yong, Deng Fenglin, Cao Changsheng, Liang Yu. CCT curves and initial corrosion properties of Q355NH steel[J]. Heat Treatment of Metals, 2021, 46(7): 84-88.

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