Submerged arc welding of S355G10+M steel: analyzing strength, distortion, residual stresses, and fatigue for offshore wind applications

This research delves into the material performance of submerged arc-welded S355G10 +M structural steel for offshore wind turbines, with an emphasis on strength, ductility, hardness, distortion, residual stress, and fatigue. This was done by conducting experiments and employing modeling tools combined with image analysis. The novelty of this study lies in examining the effects of material properties of S355G10 +M structural steel used in welded offshore wind turbine tower and monopile. The study employed a submerged arc welding (SAW) process on S355G10 +M plates of varying thicknesses by applying double V-groove and multi-pass technique. Tensile tests revealed that welded sections exhibit greater ultimate tensile strength than the base material, despite the lower yield strength. In addition, hardness and residual stresses correlate with thickness, and a potential weak point is observed at the heat-affected zone (HAZ) and base material transition. Angular distortions and axial misalignments after welding, as well as stress concentrations and residual stresses, were found to affect the fatigue performance. It was concluded that the conducted welds have sufficient quality to be exploited into industrial marine applications including offshore wind turbines.