Finite element simulation of welded P91 steel pipe undergoing post-weld heat treatment

Abstract

Residual stresses induced by fusion welding of P91 steel pipes in power generation plants can be detrimental to their integrity and mechanical performance in service. Post-weld heat treatment (PWHT) of the pipes substantially reduces the magnitude of residual stresses, mitigating their ill effects. In this paper, the residual stress field of a typically welded P91 steel pipe, reproduced from a previous publication by the authors, is subsequently subjected to PWHT for 3 h at a temperature of 760°C. A finite element model has been generated to simulate the PWHT of the pipe. Stress relaxation testing has been conducted on P91 steel uniaxial tensile specimens to obtain material property data necessary for PWHT modelling. The simulation method and the influence of PWHT on residual stresses are described.