Ni—Fe based forging superalloy excellent in high-temperature strength and high-temperature ductility, method of manufacturing the same, and steam turbine rotor

摘要

An Ni—Fe based superalloy forging material including 30 to 40 wt % of Fe, 14 to 16 wt % of Cr, 1.2 to 1.7 wt % of Ti, 1.1 to 1.5 wt % of Al, 1.9 to 2.2 wt % of Nb, 0.05 wt % or less of C and the remainder of Ni and inevitable impurities is solution-treated and aged, and thereby γ′ phase (Ni₃Al) having an initial mean particle size of about 50 to about 100 nm is precipitated. This superalloy is excellent in high-temperature strength and high-temperature ductility and can produce a large forged product of 10 ton or more. Therefore, this material is suitable for use as the material of a steam turbine rotor having a main steam temperature of 650° C. or more.