Effect of weld profiling on the fatigue strength of thin-walled rectangular hollow section T-joints made of high strength steel

Abstract

In this study, a thin-walled high-strength S960 rectangular hollow section T-joint is cyclically tested at a stress ratio of R=0.1. The work focuses on the effect of weld profiling conducted as post-weld treatment by grinding of the weld seam. Numerical simulations using the real weld seam geometry are carried out and compared with strain gauge measurements. Thereby, it is shown that the stress states of both methods are in sound agreement and the crack initiation site can be assessed well by the numerical approach. The resulting nominal S/N curves reveal an increase of the fatigue strength by about 33% at two million load-cycles due to weld profiling, which represents a high potential for this post-weld treatment technique. Furthermore, the notch stress approach using the common procedure by modelling a reference radius of r_ref=1 mm at the weld toe as well as modelling the real weld toe geometry after weld profiling are applied. The results are compared to the recently published values in the Recommendations for Fatigue Design of Welded Joints and Components by the International Institute of Welding (IIW) and highlight that both different modelling methods lead to a sound notch stress fatigue assessment of the weld-profiled condition.