Modelling FE Multi-Pass Welding in 304L Stainless Steel Cladded with Low Alloy Low Carbon Steel

Multi-pass welding is widely employed for fabricating stainless steel-cladded low-alloy carbon steel structures, where residual stresses significantly influence structural integrity and long-term performance. This study presents a computational framework to simulate the thermal and mechanical behaviour of multi-pass welding in 304L stainless steel cladded with Q345R steel, validated using experimental temperature measurements. The computational approach integrates JMatPro-derived material properties at the applicable temperature range and FE model of the welding process to accurately model temperature field, phase transformations, and residual stress evolution during welding process. Longer welding passes (i.e., inter-pass temperature of 50°C) induce higher tensile residual stresses in the transverse, through thickness and longitudinal directions (X, Y and Z, respectively) due to rapid cooling, whereas shorter passes (150°C) promote lower residual stresses. Detailed stress analysis reveals distinct stress concentrations, with the highest gradients occurring at the interface due to mismatch in the thermal properties. Heat-affected zone (HAZ) analysis shows that stress magnitudes decrease with increased welding duration, confirming the role of inter-pass cooling in mitigating stress accumulation. These findings contribute to the design of welded structures with minimised residual stress concentrations, reducing the risk of failure and improving mechanical performance.