Thermo-mechanical analysis of laser welding of Grade 91 steel plates

Generation of residual stresses and distortion in weld component is a major concern in Grade 91 steel thin plates. In the present study, FEM based Laser welding analysis of Grade 91 steel is carried out for 3 thick plates using SYSWELD software. Heat input optimization has been carried out by bead-on-plate welding at different heat input. Optimized heat input with full depth of penetration is used for a square butt joint of Grade 91 steel laser welding. Experimentally measured residual stresses using X-ray diffraction technique are compared with predicted results. Residual stresses comparison shows that due to phase transformation effect the peak tensile stress values are observed next to heat affected zone. The predicted distortion in longitudinal and transverse directions is validated with experimental results.