Residual Stress Analysis of Girth Weld for X80 Pipeline Steel Based on Contour Method

The contour method was used to measure and analyze the welding residual stress of X80 pipeline girth welds,and the distributions of circumferential and axial residual stresses of X80 pipeline girth welds were obtained. The results show that there is a significant circumferentially tensile residual stress at the center of the weld, with a maximum magnitude of about650 MPa, located at a depth of approximately 9 mm from the weld outside. The axial residual stress of the weld follows a distribution pattern of "compression-tension-compression-tension" along the wall thickness at the locations of weld center-line and weld toe. The tensile stress at the center-line of the weld reaches peak at a depth of 7-8 mm from the outside, which is about 250 MPa. The peak compressive stress is located at a depth of 16 mm of the weld thickness, with a peak value of approximately-250 MPa. The distribution of axial residual stress at the weld toe is similar to that at the center-line of the weld, but its magnitude is smaller than that at the center-line of the weld.