Fracture mechanics assessment of fatigue semi-elliptical cracks in butt-welded joints

This work carries out a theoretical study about the influence that profile geometry of the weld seam joints has on fatigue life. It is considered that SMAW butt-welded joints, 6 mm-A36 structural steel board, and the E6013 electrode. The influence of geometry is parametrized by the overweight weld and the radius of the weld toe. To do the latter, an arrangement of experiments were made into 3 levels for each factor. For the development of the current work some information obtained from experimental results was used (i.e., weld profile and mechanical properties). The geometry of one group of real weld seams is digitalized and simulated in the construction of 3D solid-models, while a superficial semi-elliptical crack is defined around the weld toe. By applying the Finite Element Method, analytical equations are obtained for the weld magnification factors (Mk). As main results of this work stand out, on the first hand, the strong influence that slub has on the fatigue life, an excess thickness means a reduction in the life forecast to even 42% for the welded joint. Secondly, the different behavior of strength intensity factor around the crack edge, which makes the crack become longer and narrower. The analytical equations for Mk can be utilized on life-management model for butt-welded joints.