Residual stresses after on-line surfacing welding repairs on the flange surface of a nuclear grade pipe end

Numerical simulations were used to study the effect of welding sequence and surfacing thickness on the residual stresses and deformation after on-line surfacing welding repair of the flange surface of a nuclear grade pipe. The simulations show that the welding sequence from the inside to the outside wall leads to smaller residual stresses and deformation due to the different thicknesses of the inside and outside walls of the flange and the rigidity differences between the connecting pipes. With a 20 mm surfacing thickness, the residual axial stress at the welding seam of the outer pipe wall is close to the material yield strength. With surfacing thicknesses no more than 15 mm thick, the residual stress at the welding seam of the outer pipe wall is far lower than the yield strength. A sample specimen was made using the optimized welding process with the residual stress then measured using X-ray diffraction. The predicted stresses agree well with the measured data to verify the simulation results. © 2020, Tsinghua University Press. All right reserved.