Residual Stresses at Weld Repairs in Pressure Vessels.

摘要

Efforts focused on developing the temperature analysis model to better represent the weld repair conditions of the HSST ITV-8vessel. Computations to study the effect of a range of weld parameters on the temperature profiles indicated that changes in weld rod size have a surprisingly small affect on the induced temperature distributions. Progress on the finite element model included (1) a study of two iteration procedures to better handle the nonlinearities of the weld repair problem, (2) an application of the model,in its present state of development,to the weld repair problem,and (3) the initiation of a study on the through-the-thickness residual stresses. It was found that the three-dimensional stiffness effects of the weld repair geometry could be included in the existing two-dimensional model. Numerical results for surface residual stresses showed improved agreement with experimental data. Progress was made in two areas for improving the representation of through-the-thickness residual stresses. First a study of a simple two-pass weld done to obtain a better understanding of the formation of the residual stress distributions in the thickness direction. Second,analyses indicated that an improved representation of the residual stress distribution through the thickness could be obtained by representing the large number of passes as a sequence of layers of weld passes.