Study on the deterioration law of mechanical properties of corroded Q355 weathering steel with 10 years’ service

Purpose This paper aims to investigate the degradation law of mechanical properties of weathering steel that had been in service for 10 years. Design/methodology/approach The monotonic tensile tests were conducted on Q355 weathering steel after corrosion. The failure morphology, stress–strain curves and the variation law of mechanical properties of steel with different degrees of corrosion were investigated. Then, a numerical simulation model considering the corrosion surface was established by using 3D reverse reconstruction technology to study the surface stress and damage development of steel with different degrees of corrosion, and to reveal the degradation law of mechanical properties of Q355 weathering steel under real service environment. Findings The degree and distribution of surface damage of specimens after corrosion had a large randomness, which lead to the specimens not reaching the strength of full net section simultaneously, and then fractured successively along the weak sections, forming a fracture form mainly with oblique fracture surface. With the increase of corrosion degree, the strength and ductility of steel at room temperature gradually decreased, and the ultimate strength and elongation after fracture decreased by up to 79.6% and 65.6%, respectively. The failure location of the specimens primarily depended on the most severely corroded regions. Originality/value The stress concentration at pits caused by localized corrosion was significant and more likely to induce damage before the specimens reached the ultimate load, thereby leading to premature failure of steel.