Martensitic stainless steel material

Abstract

A martensitic stainless steel material that has high strength and excellent SSC resistance, and also has excellent low-temperature toughness is provided. A martensitic stainless steel material of the present disclosure consists of, by mass %, C: 0.030% or less, Si: 1.00% or less, Mn: 1.00% or less, P: 0.030% or less, S: 0.0050% or less, Cr: 10.00 to 14.00%, Ni: 5.00 to 7.50%, Mo: 1.10 to 3.50%, Al: 0.005 to 0.050%, V: 0.01 to 0.30%, N: 0.0030 to 0.0500%, Ti: 0.020 to 0.150%, Cu: 1.00 to 3.50%, and Co: 0.010 to 0.500%, with the balance being Fe and impurities, and has a yield strength of 758 MPa or more. An area fraction of δ-ferrite is 5.00% or less, and a length L (μm) of the δ-ferrite in the rolling direction and a distance D (μm) between particles of the δ-ferrite in the rolling direction satisfy Formula (1): L / D ≤ 10.5 . ( 1 )

1 . A martensitic stainless steel material having a chemical composition consisting of, by mass %,
 C: 0.030% or less,   Si: 1.00% or less,   Mn: 1.00% or less,   P: 0.030% or less,   S: 0.0050% or less,   Cr: 10.00 to 14.00%,   Ni: 5.00 to 7.50%,   Mo: 1.10 to 3.50%,   Al: 0.005 to 0.050%,   V: 0.01 to 0.30%,   N: 0.0030 to 0.0500%,   Ti: 0.020 to 0.150%,   Cu: 1.00 to 3.50%,   Co: 0.010 to 0.500%,   Nb: 0 to 0.15%,   W: 0 to 1.50%,   Sn: 0 to 0.0100%,   As: 0 to 0.0100%,   Sb: 0 to 0.0100%,   B: 0 to 0.0050%,   Ca: 0 to 0.0050%,   Mg: 0 to 0.0050%, and   rare earth metal (REM): 0 to 0.0100%,   with the balance being Fe and impurities,   wherein:   a yield strength is 758 MPa or more; and   in a cross section parallel to a rolling direction of the martensitic stainless steel material,   an area fraction of δ-ferrite is more than 0 to 5.00%, and   a length L (μm) of the δ-ferrite in the rolling direction, and a distance D (μm) between a plurality of particles of the δ-ferrite in the rolling direction satisfy Formula (1):   
       
         
           
             
               
                 
                   
                     
                       L 
                       / 
                       D 
                     
                     ≤ 
                     
                       10.5 
                       . 
                     
                   
                 
                 
                   
                     ( 
                     1 
                     ) 
                   
                 
               
             
           
         
       
     
     
         2 . The martensitic stainless steel material according to  claim 1 , wherein the chemical composition contains one or more elements selected from a group consisting of:
 Nb: 0.01 to 0.15%,   W: 0.01 to 1.50%,   Sn: 0.0001 to 0.0100%,   As: 0.0001 to 0.0100%,   Sb: 0.0001 to 0.0100%,   B: 0.0001 to 0.0050%,   Ca: 0.0001 to 0.0050%,   Mg: 0.0001 to 0.0050%, and   rare earth metal (REM): 0.0001 to 0.0100%.