Precipitation Hardening Martensitic Stainless Steel and Long Blade for Steam Turbine Using the Same

Abstract

A precipitation hardening martensitic stainless steel is provided with excellent mechanical property and corrosion resistance and contains, by mass, 0.1% or less of C; 0.1% or less of N; 10.0%˜15.0% of Cr; 10.0%˜15.0% of Ni; 0.5%˜2.5% of Mo; 1.0%˜3.0% of Al; 1.0% or less of Si; 1.0% or less of Mn, and the rest is Fe and inevitable impurities. A steam turbine long blade is made of the precipitation hardening martensitic stainless steel.

1 . A precipitation hardening martensitic stainless steel comprising, by mass, 0.1% or less of C; 0.1% or less of N; 10.0%˜15.0% of Cr; 10.0%˜15.0% of Ni; 0.5%˜2.5% of Mo; 1.0%˜3.0% of Al; 1.0% or less of Si; 1.0% or less of Mn, and the rest is Fe and inevitable impurities. 
     
     
         2 . The precipitation hardening martensitic stainless steel according to  claim 1 , further comprising at least one member selected from Nb and V in an amount of 1.0% or less by mass. 
     
     
         3 . The precipitation hardening martensitic stainless steel according to  claim 1 , further comprising W, a total amount of Mo and W being the same as an amount of Mo added alone. 
     
     
         4 . The precipitation hardening martensitic stainless steel according to  claim 1 , wherein the inevitable impurities are at least one member selected from P, S, Sb, Sn, and As. 
     
     
         5 . The precipitation hardening martensitic stainless steel according to  claim 1 , wherein a temperature range of a solution treatment is 800 to 1050° C. and a temperature range of an aging treatment is 450 to 650° C. 
     
     
         6 . A steam turbine long blade using the precipitation hardening martensitic stainless steel of  claim 1 . 
     
     
         7 . The steam turbine long blade according to  claim 6 , wherein a stellite plate made of a Co-based alloy is joined to a front end portion of the blade. 
     
     
         8 . A turbine rotor comprising the steam turbine long blade of  claim 7 . 
     
     
         9 . A steam turbine comprising the turbine rotor of  claim 8 .