Martensitic stainless steel

Abstract

The martensitic stainless steel according to the invention includes, in percent by mass, 0.010% to 0.030% C, 0.30% to 0.60% Mn, at most 0.040% P, at most 0.0100% S, 10.00% to 15.00% Cr, 2.50% to 8.00% Ni, 1.00% to 5.00% Mo, 0.050% to 0.250% Ti, at most 0.25% V, at most 0.07% N, and at least one of at most 0.50% Si and at most 0.10% Al, the balance consists of Fe and impurities, and the martensitic stainless steel satisfies Expression (1) and has a yield stress in the range from 758 MPa to 862 MPa. In this way, the martensitic stainless steel has a yield stress of 110 ksi grade (a yield stress in the range from 758 MPa to 862 MPa) and the value produced by subtracting the yield stress from the tensile stress is not less than 20.7 MPa. 6.0≦Ti/C≦10.1  (1)

1 . Martensitic stainless steel, comprising, in percent by mass, 0.010% to 0.030% C, 0.30% to 0.60% Mn, at most 0.040% P, at most 0.0100% S, 10.00% to 15.00% Cr, 2.50% to 8.00% Ni, 1.00% to 5.00% Mo, 0.050% to 0.250% Ti, at most 0.25% V, at most 0.07% N, and at least one of at most 0.50% Si and at most 0.10% Al, the balance consisting of Fe and impurities, said martensitic stainless steel satisfying Expression (1) and having a yield stress in the range from 758 MPa to 862 MPa.
   6.0≦Ti/C≦10.1  (1)   
     where the symbols of the elements represent the contents of the elements in percent by mass. 
   
   
       2 . The martensitic stainless steel according to  claim 1 , further comprising at least one of at most 0.25% Nb and at most 0.25% Zr instead of part of said Fe. 
   
   
       3 . The martensitic stainless steel according to  claim 1 , comprising at most 1.00% Cu instead of part of said Fe. 
   
   
       4 . The martensitic stainless steel according to  claim 2 , comprising at most 1.00% Cu instead of part of said Fe. 
   
   
       5 . The martensitic stainless steel according to  claim 1 , comprising at least one of at most 0.005% Ca, at most 0.005% Mg, at most 0.005% La, and at most 0.005% Ce instead of part of said Fe. 
   
   
       6 . The martensitic stainless steel according to  claim 2 , comprising at least one of at most 0.005% Ca, at most 0.005% Mg, at most 0.005% La, and at most 0.005% Ce instead of part of said Fe. 
   
   
       7 . The martensitic stainless steel according to  claim 3 , comprising at least one of at most 0.005% Ca, at most 0.005% Mg, at most 0.005% La, and at most 0.005% Ce instead of part of said Fe. 
   
   
       8 . The martensitic stainless steel according to  claim 4 , comprising at least one of at most 0.005% Ca, at most 0.005% Mg, at most 0.005% La, and at most 0.005% Ce instead of part of said Fe.