Abstract
A modified version of Alloy 706, designated FENIX-700, was developed using the CALPHAD method to improve high-temperature stability above 700°C. The new alloy features reduced Nb and increased Al content, relying on γ' (Ni3Al) strengthening while eliminating γ'' (Ni3Nb), δ, and η phases. This modification improved both creep temperature capability (from 650°C to 700°C) and segregation properties. Successful manufacturing trials included a 760 mm² forging shaft using triple melt processing and a 1050 mm ESR ingot, demonstrating industrial viability. The study also explores compatible Ni-base welding materials for joining FENIX-700 to 12% Cr ferritic steel in 700°C class steam turbine applications.
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2011
ASM International
Issue Section:
Turbine Materials and Applications