Failure modes and fatigue strength of improved HSS welds

Post-weld improvement methods can significantly improve the fatigue strength of a structure. In some cases, the degree of improvement is limited by alternate failure modes. The material strength and type of loading also influence the observed fatigue crack behaviour. This study reports on crack patterns and strength for both constant and variable amplitude fatigue tests of high strength steel (HSS) welds. Some specimens were in the as-welded state, while others were post-weld treated, using methods generally categorized as residual stress modification processes. Failure modes were significantly different for CA and VA loading and VA loading showed less improvement.