Comparative evaluation of tensile properties of simulated heat affected zones of P91 steel weld joint

Abstract

ABSTRACTThe present work aims to understand the contribution made by each heat affected zone (HAZ) to the overall tensile behavior of the P91 steel weld joint. The three principal microstructures of heat-affected zones such as inter-critical (IC), fine grain (FG) and coarse grain (CG) were simulated through isothermal furnace heat treatments at 1138 K, 1208 K and 1473 K respectively. The simulated microstructures predominantly developed tempered martensite after oil quenching followed by tempering. The grain size and hardness across the P91steel weld joint vary in a complex manner. Tensile tests were carried out on each simulated HAZ and actual weld joint at 823K and a strain rate of 3 × 10-3 s-1. The weld joint specimen has failed in the base metal region. An increase in microhardness at the ICHAZ was found after tensile deformation. Higher initial strain/work hardening behavior of soft ICHAZ attributes the shifting of strain localization, consequently failure at the base metal.