INVESTIGATION THE MICROSTRUCTURE OF HEAT RESISTANT P22 AND P91 WELDS

Abstract

Heat-resistant steels P22 and P91 are often applied in boiler parts, steam pipelines, and turbine shells in a thermal power plant. The welding method is used to joint two pipes with dissimilar materials. To study the subzones and the microstructure of the dissimilar welds, this paper is based on the phase diagram, CCT continuous cooling curve, and the microstructure image obtained by optical microscope, SEM, and EDS. In addition, a soft zone is found at the P91 fusion boundary. This may be the cause of creep damage when the weld is working at high temperatures for a long time.