Hybrid Laser Arc Welding (HLAW) integrates the advantages of laser and arc welding, providing high process stability, high welding speed and penetration, narrow weld beads with a low heat input, low thermal distortion and good metallurgical properties. It is an outstanding joining process for medium and high thickness structural steels, being specially interesting for naval and offshore applications in which large panels must be 1G butt welded to manufacture larger flat panels. Although this technology has already provided appropriate results in terms of microstructure, weld morphology and static mechanical behaviour of HLAW butt joints, few studies have been yet reported regarding the fatigue behaviour.

In the present research, HLAW process was applied to join 8 mm thick structural S355J2N steel under 1G configuration. Welding tests were performed at the Advance Laser Welding Center (CASOL) available at the University of Cadiz, Spain. Different experimental welding parameters were fitted to obtain sound butt welds. The welds were subjected to different quality control tests, including visual inspection, metallographic characterization, microhardness measurements, and tensile and fatigue tests. The HLAW tests were performed at higher welding rates in 1G configuration than previously reported for 8 mm thick steels. The present contribution reports novel fatigue results for these butt hybrid welds.