AbstractThe aim of this study was to verify the mechanism of parallel heat welding (PHW) and to investigate the thermal and residual stresses due to welding. In this study, autogenous gas tungsten arc welding was used on type 304 stainless steel. Wells' one-dimensional stress distribution model was assumed to explain the behaviour of stress introduced by conventional welding (CW) and PHW processes. A step by step method proposed by Tall was applied to calculate theoretical thermal and residual stresses. Comparison between experimental and analytical results showed that the predicted results calculated using a modified Wells' model are in agreement with the experimental results, and that the elevation of equilibrium temperature during the welding process is an important mechanism for the reduction of residual stress in the PHW process. The theoretical curves of residual stress calculated for thermal cycles corresponding to CW and PHW processes show fairly good agreement with experimental results in the vicinity of the fusion zone.MST/1552