Reduction of Residual Stress in Multi-layer Welded Plates by Applying Water-shower Cooling During Welding

To reduce tensile residual stress in a welded region, we developed a new welding method that applies a water-shower behind the welding torch. When this method is applied to welding of austenitic stainless-steel plates, the water-shower cooling conditions mainly determine how much the residual stress can be reduced. To determine the conditions for reducing tensile residual stress, we first used FEM to evaluate the effects of interpass temperature on residual stress. To verify the validity of the FEM-obtained conditions, specimens welded in the case of with or without water-shower cooling were manufactured. Residual stresses in the specimens were then experimentally measured. These measurements showed that tensile residual stresses were generated on the surface of the welds and could be reduced by applying the water-shower cooling. These measurement results agree well with the results of FEM analyses. It can therefore be concluded from these analytical and experimental results that applying water-shower cooling during welding effectively reduces tensile residual stress generated by welding of austenitic stainless steel.