Superhigh temperature and pressure steam turbine.

摘要

In a superhigh temperature and pressure steam turbine including a casing, blades in the casing receiving streams of steam jets for rotation, and a rotor shaft supporting the blades for rotation, wherein the casing includes an inner casing member having static blades secured thereto for guiding the streams of steam jets and an outer casing member enclosing the inner casing member, the rotor shaft is formed of an alloy consisting essentially, by weight, of less than 0.04% C, not more than 2% Mn, not more than 1.5% Si, 10-20% Cr, 20-30% Ni, 0.5-3% Mo, 0.5-3% Ti, 0.1-0.5% Al, 0.002-0.01% B and the balance Fe and inevitable impurities. The alloy has a microstructure in which a gamma min phase is precipitated in austenite matrix, whereby the rotor shaft has superior high temperature creep strength and excellent thermal fatigue resistant property.