Fatigue strength of normal and high strength steel joints improved by weld profiling

Abstract

While some post-weld treatment techniques increase the fatigue life mainly due to induced compressive residual stress others are trying to create a smooth transition at weld toes. One of the latter is weld profiling. This study investigates the effect of weld profiling for four different steel types from S355 to S900 including one duplex stainless-steel and performs a comparison with high frequency mechanical impact (HFMI) treatment. The observed fatigue strength improvement is significantly higher than typically assumed for such techniques and comparable to increases observed for HFMI treatment. The fatigue strength further increases with parent material strength and is only slightly below the estimated fatigue strength of the parent material. Finally, fatigue design curves are proposed for weld profiling that include an increasing fatigue strength improvement for higher strength materials, but that are still conservative for low weld quality.