Experimental and numerical investigation on fatigue behaviors of Q690D butt welds

With the improvement of steel production technology, different grades of high-strength steel have been developed and widely applied in engineering, however the fatigue properties of high-strength steel need to be further studied. In this research, regarding the fatigue properties of Q690D high strength steel butt welds, experimental investigation and numerical simulation were carried out. Experimental investigations of Q690D high strength steel butt welds were performed, and properties including the basic mechanical behaviors, metallographic structure, fatigue crack growth rate and fatigue performance were obtained. The fatigue test results were compared with fatigue data from existing studies of butt welds and the Eurocode3 fatigue design S-N curve. The fatigue life prediction was performed and the fatigue crack propagation process was simulated based on the platform combining ABAQUS and Franc3D. The results show that the tested butt-welded joints specimen includes more initial defects, its fatigue properties are comparable to those of 355 MPa grade steel butt-welded joints, and the fatigue resistance advantages of high strength steels are not obvious. The simulated results are in good agreement with the fatigue test results, indicating the proposed simulation method is applicable in the fatigue life assessment of engineering structures with known initial defects. The proposed simulation method provided a numerical analysis approach to the fatigue assessment of engineering structures, thereby reducing the cost of fatigue tests and bringing significant economic and social benefits.