锈损冷成型钢表面形貌及力学性能

Surface Morphology and Mechanical Properties of Corroded Cold-formed Steel

为研究锈蚀对冷成型钢表面形貌特征和力学性能的影响,对工业环境下服役10 a的冷成型钢进行表面三维形貌扫描、单调拉伸试验和断口扫描,得到了锈蚀钢材表面二维和三维形貌图、锈蚀损伤参数、应力-应变曲线、力学性能指标以及微观断口形貌图,并分析了锈蚀损伤参数、力学性能指标的变化规律,最后建立了锈蚀冷成型钢材料本构模型.结果表明:随着锈蚀程度增加,钢材表面蚀坑数量减少且蚀坑形貌发生明显变化,均匀锈蚀所占比例、最大蚀坑深度逐渐增大,锈蚀钢材表面变得越来越粗糙;弹性模量、屈服强度、极限强度、断后伸长率随材料损失率的增加呈线性下降趋势,屈服平台变短甚至消失,宏、微观断口形貌变化明显,并且所建立的本构模型能够精准地反映锈蚀冷成型钢应力-应变曲线的变化趋势.

Three-dimensional morphology scanning,monotonic tensile test,and fracture scanning of cold-formed steel with 10 years of service in the industrial environment were performed to investigate the effect of corrosion on the surface morphology and mechanical properties of cold-formed steel.The two-dimensional and three-dimensional surface topography,corrosion damage parameters,stress-strain curves,mechanical property indexes,and microscopic fracture topography of the corroded cold-formed steel were obtained.The variation rules of the corrosion damage parameters and mechanical property indexes were also analyzed.Finally,a constitutive model of the corroded cold-formed steel was established.The results indicate that the number of corrosion pits on the steel surface decreased,and the morphology of corrosion pits changed significantly with the increase in corrosion degree.The proportion of the uniform corrosion and maximum depth of the corrosion pits gradually increased,and the surface of the corroded steel became increasingly rougher.The elastic modulus,yield strength,ultimate strength,and elongation after fracture linearly decreased with an increase of the material loss rate.The yield platform also became shorter or even disappeared.Moreover,the macrofracture and microfracture morphologies changed obviously.The established constitutive model can accurately reflect the variable trend of the stress-strain curve of the corroded cold-formed steel.