Experimental and numerical investigation of residual stresses in dissimilar butt-weld joint made of cast iron and mild steel

Dissimilar welded joints, formed by joining materials with different mechanical and chemical properties, present significant challenges in terms of design and manufacturing. This is mainly due to the different properties of the materials, which exhibit different behaviours when they are subjected to high thermal gradients. The joint consisted of dissimilar materials, spheroidal cast iron (GJS500-7) and structural steel (S355) welded using the Flux-Cored Arc Welding (FCAW) process. The research focuses on analysing the effects of thermal gradients, due to welding, on residual stresses and deformation on the welded joint. To this aim, Finite Element Method (FEM) was used to simulate the thermo-mechanical behaviour of the joint during the welding process to predict both the distortions and the residual stresses distribution. The numerical results are in accordance with the experimental ones, providing good confidence in the use of the model to predict residual stresses and distortions for this type of application.