Effect of nickel-based filler metal types on creep properties of dissimilar metal welds between Inconel 617B and 10% Cr martensitic steel

Creep rupture behaviors of dissimilar metal welds (DMWs) between Inconel 617B and 10% Cr martensitic steel with two different filler metals Inconel 617 and 82 were comparatively investigated at 600 degrees C to study the effect of nickel-based filler metal types on creep properties. Both the crept DMWs ruptured on the steel side prematurely compared to steel base metal (BM). The failure mode of DMW shifts from interfacial failure at weld metal (WM)/ steel interface to Type IV crack in the intercritical heat-affected zone (ICHAZ) of steel with longer rupture life at the same creep condition by replacing Inconel 617 filler metal with Inconel 82. Type IV crack was related to matrix softening and fine prior austenite grain boundaries (PAGBs) scarcely decorated by precipitates in the ICHAZ. Interfacial failure was controlled by creep voids nucleation, growth and coalescence at the interface, while oxide notch only triggered crack initiation. The failure mode shift is because Inconel 82 filler metal compared to Inconel 617 can achieve slighter creep deformation concentration in the HAZ closely adjacent to interface and avoid interfacial failure of the DMW due to the lower creep strength gradient across the interface it induced. Based on this study, creep strength compatibility should be considered when selecting nickel-based filler metals for similar DMWs to obtain prolonged creep life. (C) 2021 The Author(s). Published by Elsevier B.V.

Automated summary

The study compared the creep rupture behaviors of dissimilar metal welds using different nickel-based filler metals, revealing that using Inconel 82 filler metal instead of Inconel 617 can prevent interfacial failure of DMWs by reducing creep deformation concentration in the heat-affected zone adjacent to the interface. Therefore, creep strength compatibility should be considered when selecting nickel-based filler metals for prolonged creep life in similar DMWs.