Influence of Heat Treatment in Residual Stresses Generated in P91 Steel-pipe Weld

The knowledge of residual stress arising from the welding processes is extremely important because the mechanical properties of the welded components are not only determined by the microstructures present in the joint, but also by the heterogeneous residual stresses introduced during the thermal cycle in welding processes. The aim of this work is the characterization of ASTM P91 steel-pipe welded by Metal Cored Arc Welding & Flux Cored Arc Welding (MCAW/FCAW) processes, through the residual stresses evaluation associated with welding and post-weld heat treatment (PWHT). Residual stresses were analysed by X-ray diffraction technique with sin(2)psi method, presenting tensile behaviour with higher magnitude at the weld metal of root region. The PWHT promoted the relief of the residual stresses in the both regions. High Vickers microhardness values were observed in the weld metal region before the PWHT, which was very efficient to reduce them.