STEAM TURBINE UTILIZING STEAM TURBINE BLADE, AND STEAM TURBINE POWER GENERATION PLANT UTILIZING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a low-pressure steam turbine utilizing a long blade which has the length of a specific value or more with respect to a specific number of revolutions, and are made of martensite in which a V-notch impact value and tensile strength is a specific value or more.;SOLUTION: A steam turbine blade has an airfoil portion 51 with the length of 45 in. or more when a number of revolutions is 3000 rpm, or the length 37.5 in. or more when a number of revolutions is 3600 rpm. At the vicinity of an inset portion 52, the airfoil portion is in parallel with a rotation axis, while at the end of the airfoil portion 51, it tilts slightly with respect to the rotational axis in the airfoil portion width direction. The inset portion 52 has a fork shape having 9 or more portions, or 7 or more portions when the airfoil portion 51 has the length of 45 in. or more, or 37.5 in. or more, respectively, or has a reverse Christmas-tree shape having protrusions of 4 shoulders or more. Further, the steam turbine blade is made of martensite steel having a V-notch impact value of 6 kgm/cm2 or more and tensile strength of 140 kg/cm2 or more at 20°C. The martensite steel contains, by weight, 0.13-0.40%C, 10.5% or less S, 1.5% or less Mn, 2-3.5% Ni, 8-13% Cr, 1.5-4% Mo, 0.02-0.3% Nb and/or Ta, 0.05-0.35% V, and 0.04-0.15% N.;COPYRIGHT: (C)2001,JPO