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

To provide an Ni-Fe based forging superalloy which is excellent in high-temperature strength and high-temperature ductility and which can be manufactured to a large forged product of 10 ton or more, a method of manufacturing the same, and a steam turbine rotor formed of an Ni-Fe based superalloy forging material. 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 A1, 1.9 to 2.7 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 ³' phase (Ni 3 Al) 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 the material of steam turbine rotor having main steam temperature of 650°C or more.