Life Prediction of T91 Welded Joint and its Engineering Application Under Consideration of Welding Residual Stresses

Welding residual stresses (WRS) of welded joint have been a problem for long time. At present experiment and numerical simulation technology can be used to determine the distribution of WRS. ABAQUS codes were used to calculate WRS for welded joint of T91 tube and obtain the stress distribution under internal pressure (IP) and bending moment (BM) with WRS. ABAQUS user subroutine of the modified Kachanov-Rabotnov (K-R) constitutive equations was developed to calculate creep damage of welded joint on consideration of WRS. The distribution of stress and creep damage was obtained for the tube at different service time. Although the WRS relax at initial stage rapidly at high temperature condition, the accumulative damage caused by initial stress has much effect on the welded joint. Finally life prediction method of T91 welded joint with WRS on the basis of creep damage was proposed, which was compared with the results by DL/T 940-2005, API 579, and L-M method. The results in present paper are in good agreement with experiment result.