The Effects of Postwelding Heat Treatment on Microstructural Evolution of Laser Welded V-4Cr-4Ti Alloy

To investigate the effect of postwelding heat treatment (PWHT) on jointed materials, laser welded V-4Cr-4Ti alloy (NIFS-HEAT2) was used in this study. The hardening of the weld metal was effectively reduced by PWHT at 873K. The microstructure of after PWHT showed that formation of precipitate free (PF) areas and precipitate segregated areas (PS) in only welded metal. The samples with and without PWHT were irradiated in the temperature range of 573-873K up to the dose of 12 dpa. After the irradiation, microstructure and Vickers hardness of the welded sample were compared of base metal. The effects of PWHT on weld metal, effectively improve for the hardness for unirradiated samples and for alloys irradiated at lower temperatures, are not effective or have a very limited effect at higher temperature irradiation where plate like Ti(CON) precipitates were formed