Estimation of residual stress distribution of Alloy600/SUS304 dissimilar weld joint

This paper describes the estimation of residual stress distribution of Alloy600/SUS304 dissimilar weld joint in the nuclear power plant piping. The calculated results by two-dimensional axi-symmetric finite element method (FEM) modeling were compared with the measurements by non-destructive methods of the X-Ray diffraction and strain gauge procedures. In the thermal elasto-plastic analysis, two factors were considered. One is the geometric modeling of weld deformation and another is the modeling of heat flux in welding. Though thermal histories were affected by the modeling of weld deformation and heat flux, estimation of residual stress was robust to the modeling. Applicability of X-Ray diffraction method is also confirmed to measure axial residual stress at the surface of the welded piping, because the scatter between measured and calculated results were less than 50 MPa. It was confirmed that the axial residual stress distribution near the weld joint of Alloy600/SUS304 piping is estimated by FEM analysis and X-Ray diffraction method within acceptable accuracy. (author)