Experimental and numerical investigation on mechanical and fatigue performance of corroded Q690D high-strength steel

As a prevalent environmental factor in the service process of steel structures, corrosion have a significant impact on the mechanical and fatigue properties of steel, thus deteriorating service safety. In this article, focused on corroded Q690D high-strength steel, experimental and numerical investigations have been performed. Electrolytic accelerated corrosion experiments were conducted, and 3D surface morphology measurements were employed to analyse the surface properties of specimens with various corrosion degrees. Mechanical and high-cycle fatigue tests were carried out on the corroded specimens, then degradation models between the mechanical behaviours and corrosion characteristics were established. Furthermore, the fatigue damage evolution model of Q690D high-strength steel was calibrated based on continuum damage mechanisms (CDM), and numerical simulations of the corroded specimen corresponding to the monotonic tensile tests and high cycle fatigue tests were conducted. The results show that with the increase of corrosion degree, the elastic modulus, yield stress, and tensile stress would decrease, and the fatigue performance would deteriorate. Corrosion has a greater effect on the fatigue life of long-life range and the slopes of the S-N curves after corrosion are more uniform. With the CDM parameters of non-corroded Q690D and the numerical model with consideration of surface roughness, the fatigue life of corroded Q690D could be well simulated.