Analysis of Residual Stress in Stainless Steel Pipe Weld Subject to Mechanical Axial Tension Loading

This paper presents the characteristics of welding residual stresses in circumferentially butt-welded stainless steel pipe by utilizing three-dimensional (3-D) uncoupled thermo-mechanical finite element (FE) analysis method. Moreover, stress variations in welded joints of the pipe under superimposed mechanical axial tension loading are further investigated employing the welding residual stresses and plastic strains obtained from the thermo-mechanical FE analysis as an initial condition. Results show that spatial variations of the welding residual stresses are present along the circumference and a rapid change of the residual stresses exists at the welding start/stop position, hence 3-D FE analysis is essential to accurately simulate circumferential welding of a pipe component. When mechanical axial tension loading is applied to the circumferentially butt-welded stainless steel pipe, bending moment is generated at the welded joints caused by the circumferential shrinkage of the weld region during welding; thus affecting the axial and hoop stress evolutions in the course of the superimposed mechanical loading.