Duplex stainless steel material

Abstract

A duplex stainless steel material according to the present disclosure consists of, by mass %, C: 0.030% or less, Si: 0.20 to 1.00%, Mn: 0.50 to 7.00%, P: 0.040% or less, S: 0.020% or less, Al: 0.100% or less, Ni: 4.20 to 9.00%, Cr: 20.00 to 30.00%, Mo: 0.50 to 2.00%, Cu: 1.50 to 4.00%, N: 0.150 to 0.350%, and V: 0.01 to 1.50%, with the balance being Fe and impurities, and satisfies Formula (1) described in the description. A microstructure consists of, in volume ratio, ferrite in an amount of 30.0 to 70.0% with the balance being austenite. The yield strength is 586 MPa or more. A number density of Cu precipitates having a major axis of 50 nm or less in the austenite is 150 to 1500/μm 3 .

1 . A duplex stainless steel material consisting of, by mass %,
 C: 0.030% or less,   Si: 0.20 to 1.00%,   Mn: 0.50 to 7.00%,   P: 0.040% or less,   S: 0.020% or less,   Al: 0.100% or less,   Ni: 4.20 to 9.00%,   Cr: 20.00 to 30.00%,   Mo: 0.50 to 2.00%,   Cu: 1.50 to 4.00%,   N: 0.150 to 0.350%,   V: 0.01 to 1.50%,   Nb: 0 to 0.100%,   Ta: 0 to 0.100%,   Ti: 0 to 0.100%,   Zr: 0 to 0.100%,   Hf: 0 to 0.100%,   W: 0 to 0.200%,   Co: 0 to 0.500%,   Sn: 0 to 0.100%,   Sb: 0 to 0.100%,   Ca: 0 to 0.020%,   Mg: 0 to 0.020%,   B: 0 to 0.020%, and   rare earth metal: 0 to 0.200%,   with the balance being Fe and impurities,   and satisfying Formula (1),   wherein:   a microstructure consists of, in volume ratio, ferrite in an amount of 30.0 to 70.0% with the balance being austenite;   a yield strength is 586 MPa or more; and   in the austenite, a number density of Cu precipitates having a major axis of 50 nm or less is 150 to 1500/μm 3 ;   
       
         
           
             
               
                 
                   
                     
                       
                         C 
                         ⁢ 
                         r 
                       
                       + 
                       
                         
                           3 
                           . 
                           3 
                         
                         ⁢ 
                         
                           ( 
                           
                             
                               M 
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                               o 
                             
                             + 
                             
                               
                                 0 
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                                 5 
                               
                               ⁢ 
                               W 
                             
                           
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                     ( 
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         where, a content in percent by mass of a corresponding element is substituted for each symbol of an element in Formula (1), and if a corresponding element is not contained, “0” is substituted for the symbol of the corresponding element. 
       
     
     
         2 . The duplex stainless steel material according to  claim 1 , containing one or more elements selected from a group consisting of:
 Nb: 0.001 to 0.100%,   Ta: 0.001 to 0.100%,   Ti: 0.001 to 0.100%,   Zr: 0.001 to 0.100%,   Hf: 0.001 to 0.100%,   W: 0.001 to 0.200%,   Co: 0.001 to 0.500%,   Sn: 0.001 to 0.100%,   Sb: 0.001 to 0.100%,   Ca: 0.001 to 0.020%,   Mg: 0.001 to 0.020%,   B: 0.001 to 0.020%, and   rare earth metal: 0.001 to 0.200%.