| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel for steam turbine blades which is high in strength and toughness enough to attain both 1450 MPa or higher in strength at 0.2% proof stress and 15 J or more in absorbed energy of charpy impact test.SOLUTION: A steel for steam turbine blades has a composition which contains, by mass, 0.02-0.10% of C, up to 0.25% of Si, 0.001-0.10% of Mn, up to 0.010% of P, up to 0.010% of S, 8.5-10.0% of Ni, 10.5-13.0% of Cr, 2.0-2.5% of Mo, 0.001-0.010% of N, 1.15-1.50% of Al, less than 0.10% of Cu, up to 0.20% of Ti, and the remainder being incidental impurities and Fe, and which satisfies formulae (1), (2) and (3) as follows: formula (1): 6.0≤Ni/Al≤8.0; formula (2): 9.0≤Nieq≤11.0; and formula (3): 17.0≤Creq≤19.0. |
