Experimental research on fatigue performance of butt welds of corroded Q690 high strength steel

Abstract The marine environment was characterized by high humidity and high salinity. Offshore structures faced erosion damage caused by the spray splash, structural durability was severely challenged and tested. In this paper, by simulating the corrosion environment of splash zone, the fatigue test of butt welds of Q690 high strength steel was carried out, and the S N curves of different periods were compared to analyze the influence of corrosion damage on fatigue performance of butt welds of HSS. Based on the damage theory, the degradation law of mechanical properties of specimen was studied. The results show that as the corrosion period increases, more corrosion products were distributed at the butt welds, and the metallic luster gradually darkens. The rust rates of 100 days of corrosion was 8.46%, and the corrosion depth rates of WZ and HAZ were 1.34 mm/a and 1.46 mm/a, respectively. The fatigue limit value of specimen was reduced by 32.7% under high cycle loading. According to the scan results of failure fractures, weld defects and corrosion damage have a greater impact on crack propagation. The damage curve can reflect the fracture formation mechanism. When the stress level was large, the number of fatigue striations decreases, and the cumulative amount of damage gradually increases. The research results are of great significance to the practical engineering application of Q690 high strength steel.