| 摘要 |
PURPOSE:To improve the creep characterstic at a high temp. by producing the rotor of a steam turbine by forging of a Cr-Mo-V low-alloy steel added with Nb or Ta and subjecting the same to a heat treatment under specific conditions. CONSTITUTION:A Cr-Mo-V low-alloy steel contg. 0.15-0.30% C, <0.1% Si, <1.0% Mn, 0.1-1.0% at least one kind of Ni and Co, 0.5-3.0% Cr, 0.3-1.5% Mo, 0.1-0.3% V and 0.1-0.30% at least one kind of Nb and Ta and contains further at least 1 kind among 0.002-0.015% B, 0.02-0.1% N and 0.5-2.0% W is forged to manufacture a rotor blank material for a steam turbine. The blank material is annealed at 1,050-1,150 deg.C and is then subjected to a hardening treatment from 980-1,070 deg.C and further to tempering at 600-750 deg.C. The creep characteristic at a high temp. is improved and the failure of the rotor during use is prevented. |
