PURPOSE: To obtain a heat resistant steel provided with high creep rupture strength at high temp. and high toughness by adding very small amounts of Al and W to a high Cr martensitic alloy steel contg. optimum amounts of C, Si, Ni, MO, V, Nb, N, etc.
CONSTITUTION: This heat resistant steel contains, by weight, 8W13% Cr, 0.5W2% Mo, 0.02W0.5% V, 0.02W0.15% Nb, 0.025W0.1% N, 0.05W0.25% C, 0% or ≤0.6% Si, ≤1.5% Mn, ≤1.5% Ni, ≤0.02% Al and 0.1W0.65% W and has practically a perfectly tempered martensite structure. By this steel composition the metallurgical structure is kept stable even after long-time heating at high temp., and the long-time creep rupture strength at high temp. is improved without deteriorating the toughness. This heat resistant steel is suitable for use as the material of a rotor for a high efficiency steam turbine.
KIRIHARA SEISHIN
KURIYAMA MITSUO
YOSHIOKA TAKATOSHI
SASAKI RIYOUICHI