Investigation of the mechanical properties of steel plates with artificial pitting and the effects of mutual pitting on the stress concentration factor

摘要

Pitting corrosion in steel structures reduces the cross-sectional area of steel members and generates stress concentrations, which degrade the bearing capacity of steel members, thereby causing structural collapse. This paper studied the relationship between pitting corrosion and the stress concentration factor (SCF) under tensile loading and the effects of pitting corrosion on the mechanical properties and deformation of specimens. First, mechanical drilling and milling methods were used to fabricate artificial pitting on small specimens to simulate natural corrosion. The effects of the pitting depth and diameter on the mechanical properties and deformation capacity of the specimens were studied. Then, a digital image correlation (DIC) system was employed to measure the surface strain field of the specimens, and the differences between the local deformation around the pitting and the overall deformation of the specimen were investigated. Finally, a numerical method was applied to study the effects of pitting size parameters, pitting position parameters, plate thickness and double pitting on stress concentrations. The results showed that the reason for the degradation in the mechanical properties and deformation ability of the specimen was the joint effect of cross-sectional reduction and stress concentrations around the pitting. A double yield phenomenon was observed because the deformation near the pitting occurred more rapidly than the deformation of the rest of the specimen. The maximum value of the SCF occurred when the pitting was at the edge of the component. If the ratio of the plate thickness to the corrosion pitting depth was less than 5, the effects of the plate thickness on the stress concentration were obvious. The location of the critical area around the double pitting was affected by the position parameters.