METHOD FOR MITIGATING RESIDUAL STRESSES IN WELDED METAL COMPONENTS USING HIGH TORCH TRAVEL SPEEDS

A process for providing a significant improvement in the detrimental tensile residual stress condition on the root side of welds, especially on the insid e wall of piping welds. The method uses a high welding torch travel speed (10 inches/min), especially on the last one or two cap passes. The process relie s on the limited thermal heat sink capability of the pipe wall and nearly completed weld joint itself to generate a significant through-wall temperatu re gradient, and therefore a sufficient through-wall stress gradient during the welding. This stress gradient results in metal plasticity and permanent strains, and therefore a reduction in the magnitude of the final residual stress or, preferably as conditions allow, a reversal in the direction of th e stresses from tensile to compressive. The method can be used as a welding process or as a heat treatment. In the case of heat treatment, the far surfa ce of the weld joint is heated without fusion of the material making up the far surface.