Effects of Post Weld Heat Treatment (PWHT) Temperature on Mechanical Properties of Weld Metals for High-Cr Ferritic Heat-Resistant Steel

Welded joints of high-Cr ferritic heat-resistant steel, ASTM A335 Gr. P91, were subjected to post weld heat treatment (PWHT) to improve mechanical properties and to reduce residual stress. We have measured the A c1 of weld metals for Gr. P91 steel, containing varying amounts of Mn+Ni, and have examined the effects of PWHT temperatures on the mechanical properties of each weld metal. The upper limits of the PWHT temperature for the respective weld metals are considered.