Experimental Research on Fatigue Performance of Corroded Q690 High-Strength Steel

Abstract

To study the antifatigue performance of Q690 high-strength steel in the ocean splash zone, indoor accelerated corrosion tests and high-cycle fatigue tests were carried out, and the S-N curves of different corrosion specimens were fitted. The law of fatigue crack growth was determined using a scanning electron microscope. The results showed that as the degree of corrosion damage increased, the surface of steel lost its metallic luster, and reddish-brown layered corrosives gradually formed. After 100 days of corrosion, the rust rate and corrosion depth rate of specimens were 7.21% and 1.342 mm/year, respectively. Under cyclic loading, the fatigue limit value of corrosion specimens was reduced by 38.89% due to the influence of external corrosion damage, which accelerates the fatigue performance degradation rates of specimens. The damage index can reflect the crack distribution law of failure fracture. When the stress level increases, the number of fatigue bands decreases, and the damage accumulation increases. The research results are of great significance for the fatigue failure prediction and reliability analysis of Q690 high-strength steel.