Fatigue properties of arc-welded lap joints with weld start and end points

Fatigue properties of arc-welded lap joints with weld start and end points were investigated through experiments with 2.3-mm and 3.2-mm thick 440 MPa-class steel sheets. Macroscopic fatigue crack-initiation sites depended on the length of the weld bead to the specimen width. In joints with shorter weld beads, cracks mainly initiated at the toe of the weld start points, while joints with longer beads had initial cracks at the toe of the bead centre. Crack-propagation analyses, taking stress distribution around the weld toe and residual stress into account, suggested that residual stress distribution could move crack-initiation sites from the weld start point to the bead centre, although the applied stress at the toe of the weld start point remains the highest.