Mechanical Property Model of Q620 High-Strength Steel with Corrosion Effects

Abstract

High-strength steel (HSS) is widely used in engineering structures, due to its superior material performance, but corrosion tends to occur in steel structures with time. The corrosion effects on mechanical performance of Q620 HSS were investigated experimentally. The electrochemical accelerated corrosion test was conducted to generate corroded Q620 HSS specimens (ρ = 0~60%). With increases in the corrosion degree, corrosion performance became more and more non-uniform. The tensile coupon test was conducted to clarify mechanical properties of corroded Q620 HSS specimens. With increases in corrosion degree, fy, fu, εu and E decreased, correspondingly. The effect of corrosion on εy could be ignored. With the deepening of corrosion, the necking of Q620 HSS specimens was weakened, which reduced their ductility. The simplified constitutive model consisting of nominal yield point (εy, fy) and ultimate point (εu, fu) was proposed to quantify the mechanical properties of Q620 HSS with different corrosion degrees. After the numerical fitting, relationships between the corrosion degree and mechanical properties were clarified. Based on the results of numerical fitting, mechanical properties of corroded Q620 HSS specimens were worse than those of specimens with idealized uniform corrosion. The adverse effect of corrosion on εuc was more obvious than that on strength properties. Comparison among different mild steels and HSSs was performed. Different indexes were chosen to clarify corrosion effects on the ductility of corroded Q620 HSS specimens. This study considers and discusses the research on corrosion rates, the relationships between service time, service environment, corrosion form and strength properties of Q620 HSS.