Fatigue behavior of low alloy structural steel single-lap bolt-welded joint

Abstract The fatigue behavior of Q345B low alloy structural steel single-lap bolt-welded joint is studied compared to bolted and welded joints. A series of static and fatigue experiments of bolt-welded, bolted and welded joints were carried out, and its static finite element analysis were performed. The experiments showed that the fatigue failure modes of bolt-welded and welded joints are fatigue fracture at weld toe. With the increase of stress levels, the location of crack initiation trends to move from weld toe to weld root. Compared to welded and bolted joints, the usage of welds and bolts in bolt-welded joint can enhance fracture resistance of the joint. The welds and bolts of bolt-welded joint can improve the bearing capacity. The nominal stress, hot spot stress (HSS) and local strain energy density (SED) approaches were used to estimate fatigue life of bolt-welded and welded joints. The local SED of bolt-welded joint shows a smaller scatter band in fatigue life estimation compared to the nominal stress and HSS method. The results showed the bolt-welded joint has a higher fatigue strength, and the fatigue assessment of bolt-welded joint under local SED can better estimate the fatigue life. This study provides theoretical and experimental references for the fatigue design of single-lap bolt-welded joint.