Asymptotic residual stress distribution induced by multipass welding processes

In the high cycle fatigue (HCF) regime, the fatigue strength of welded joints is influenced by residual stresses (RS) induced during welding processes. If the weld toe is modelled via a sharp V-notch, the distribution of weld toe residual stress can be shown to be asymptotic with a singularity which follows either the linear-elastic or elastic-plastic solution depending on parameters that range across material properties, specimen clamping conditions, and the welding process. For thicker plates, multipass welding is used instead of single-pass welding to reduce the heat input and hence the width of the fusion zone (FZ) and heat-affected zone (HAZ). However, for a fixed plate thickness, the magnitude and extent of residual stresses near the weld toe will vary according to the number of passes used in the welding operation. In this paper the influence of multipass welding on the residual stress field near the weld toe has been analysed using a combination of analytical and numerical techniques. It was found that the higher the number of weld passes, the higher the magnitude of the residual asymptotic stress field near the weld toe.