Effect of Post-Weld Heat Treatment Temperature on the Mechanical Properties and Microstructure of Weld Heat-Affected Zone of 2.25Cr-1Mo Steel

The effect of post-weld heat treatment (PWHT) temperature on the mechanical properties of the heat-affected zone (HAZ) of 2.25Cr-1Mo steels was investigated. SA-387 Gr. 22 Cl. 2 steel was employed, and the specimens taken from the steel were thermally cycled using Gleeble to simulate the coarse-grained HAZ (CGHAZ), fine-grained HAZ (FGHAZ), and intercritical HAZ (ICHAZ). Before the PWHT, the simulated HAZs exhibited poor impact toughness as compared with the base metal. The base metal and simulated HAZ specimens were heat treated in a furnace at 610, 650, 690, and 730℃ for 8 h; their impact toughness improved significantly irrespective of the PWHT temperature. The microstructural changes owing to the PWHT were observed using scanning electron microscopy and correlated with the mechanical properties.