Effect of Welding Technologies on Decreasing Welding Residual Stress of Francis Turbine Runner

On basis of the subsection welding and the local heating's reasonable technological parameters obtained by plane experiment the welding residual stress field of some Francis turbine runner is regulated and controlled For the experimental plane with a thickness of 16 mm, the effect of subsection welding on decreasing welding residual stress of the prior welding section is obvious when the distance is less than 50 mm away from the end of latter welding section For the local heating the best position where the effect on decreasing the welding residual stress of plane is best is 60 mm or so away from the edge of heating area The experimental results of runner show that the subsection welding can make the residual compressive stress engender in the blade dangerous area while the stress value is greatly influenced by the length of the welding section of blade outlet The local heating can further decrease the value of residual stress near blade outlet while the local heating processed after heat treatment is better than that processed before heat treatment