To obtain a turbine disk satisfying required mechanical properties by constituting a turbine disk of a martensitic heat resistant steel in which the average crystalline grain size of the outside peripheral part of the part on which a turbine blade is to be planted is regulated so that it is larger than that of the central part.
A turbine disk 8 is constituted of a martensitic heat resistant steel in which the average crystalline grain size of the outside peripheral part of the part on which a turbine blade 3 is to be planted is regulated so that it is larger than that of the central part. The outside peripheral part is hardened at a temp. higher than hardening temp. for the central part and the central part is hardened at a temp. lower than hardening temp. for the outside peripheral part, followed by tempering refining heat treatment. The martensitic heat resistant steel has a composition consisting of, by weight, 0.08-0.18% C, ≤0.1% Si, ≤0.5% Mn, 1.5-3.0%, preferably 2.0-3.0%, Ni, 10-12.5% Cr, 1.5-3.0%, preferably 1.7-2.7%, Mo, 0.15-0.35% V, 0-0.15%, preferably 0.04-0.15%, Nb, 0.03-0.10%, preferably 0.04-0.10%, N, ≤0.0002% H, and the balance Fe with inevitable impurities.
KONNO SHINYA
NAKAMURA SHIGEYOSHI
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