Experimental and computational investigation of weathering steel Q450NQR1 under high cycle fatigue loading via crystal plasticity finite element method

The fatigue properties of the Q450NQR1 steel were experimentally and computationally investigated. The experimental results show a large scatter of the fatigue lifetime under the high cycle fatigue loading. Based on the Voronoi diagram and crystal plastic model, a polycrystalline representative volume element (RVE) model with a pore or inclusion was constructed to analyze the effect of local stress–strain on the high cycle fatigue (HCF) and very-high-cycle fatigue (VHCF) life. Computational results show that the large deformation mostly occurs at the grain with a large Schmid factor. The increment of the mean accumulated plastic strain of the critical grain was proposed as the fatigue indicator parameter (FIP). A fatigue model was suggested based on the FIP, and the fatigue model can describe the influence of the material microstructures on fatigue life. The fatigue life curve with different sizes of defects was plotted and it is found that inclusions are the major factor in fatigue life dispersion. © 2022 Elsevier Ltd