Effect of weld residual stress on fatigue strength

Residual stress (RS) refers to the stress permanently present in structures without any external load. This stress can be introduced by different sources, for instance, weld, post‐weld treatment, etc. Weld is a joining process that is associated with intensive heating which leads to considerable change in local material microstructure and the formation of high residual stresses in the welded joint. Residual stress introduces a change in the stress ratio, which means a change in the characteristic of cyclic loading which can have a detrimental effect on the fatigue strength of welded joints. In this paper, an experimental and numerical study of weld residual stress through the thickness direction at the weld toe of transversal attachment made with S355 was investigated. It was found that weld induced compressive residual stress at the surface. In the case where weld induces compressive residual stress, the fatigue life is 4.5 times higher than the standard as‐welded S‐N curve (when tensile residual stress is introduced)