US2022145438A1PendingUtilityA1

Duplex stainless steel material

Assignee: NIPPON STEEL CORPPriority: Aug 19, 2019Filed: Aug 18, 2020Published: May 12, 2022
Est. expiryAug 19, 2039(~13 yrs left)· nominal 20-yr term from priority
C21D 8/02C22C 38/04C21D 9/46C21D 1/18C21D 9/08C21D 6/005C21D 8/10C21D 8/0226C21D 6/004C22C 38/48C22C 38/002C22C 38/58C22C 38/44C22C 38/50C22C 38/54C22C 38/06C22C 38/001C22C 38/005C22C 38/46C22C 38/02C22C 38/42
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Claims

Abstract

The duplex stainless steel material according to the present disclosure has a chemical composition consisting of, in mass %, C: 0.030% or less, Si: 0.20 to 1.00%, Mn: 0.50 to 7.00%, P: 0.040% or less, S: 0.0100% or less, Al: 0.100% or less, Ni: 4.20 to 9.00%, Cr: 20.00 to 28.00%, Mo: 0.50 to 2.00%, Cu: 1.90 to 4.00%, N: 0.150 to 0.350%, V: 0.01 to 1.50%, and one or more types of element selected from the group consisting of Ca: 0.0001 to 0.0200% and Mg: 0.0001 to 0.0200%, with the balance being Fe and impurities, and satisfying Formulae (1) and (2) described in the description, a microstructure consisting of 35.0 to less than 50.0% of ferrite in volume ratio and austenite as the balance, and a yield strength of 550 MPa or more.

Claims

exact text as granted — not AI-modified
1 . A duplex stainless steel material comprising:
 a chemical composition consisting of, in mass %,   C: 0.030% or less,   Si: 0.20 to 1.00%,   Mn: 0.50 to 7.00%,   P: 0.040% or less,   S: 0.0100% or less,   Al: 0.100% or less,   Ni: 4.20 to 9.00%,   Cr: 20.00 to 28.00%,   Mo: 0.50 to 2.00%,   Cu: 1.90 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%,   B: 0 to 0.0200%, and   rare earth metal: 0 to 0.200%, and   one or more types of elements selected from the group consisting of:   Ca: 0.0001 to 0.0200%, and   Mg: 0.0001 to 0.0200%,   with the balance being Fe and impurities,   satisfying Formulae (1) and (2);   a microstructure consisting of 35.0 to less than 50.0% of ferrite in volume ratio and austenite as the balance; and   a yield strength of 550 MPa or more:   
       
         
           
             
               
                 
                   
                     
                       
                         4 
                         . 
                         5 
                       
                       ⁢ 
                       0 
                     
                     ≤ 
                     
                       Mn 
                       + 
                       Cu 
                     
                     ≤ 
                     9.50 
                   
                 
                 
                   
                     ( 
                     1 
                     ) 
                   
                 
               
               
                 
                   
                     
                       
                         13 
                         × 
                         Cr 
                       
                       - 
                       
                         19 
                         × 
                         Ni 
                       
                       + 
                       
                         21 
                         × 
                         Mo 
                       
                       - 
                       
                         17 
                         × 
                         Cu 
                       
                       + 
                       
                         63 
                         × 
                         Mn 
                       
                       + 
                       
                         8 
                         × 
                         Si 
                       
                       + 
                       
                         984 
                         × 
                         N 
                       
                     
                     ≥ 
                     580 
                   
                 
                 
                   
                     ( 
                     2 
                     ) 
                   
                 
               
             
           
         
         where, a content in mass % of a corresponding element is substituted for each symbol of an element in Formulae (1) and (2). 
       
     
     
         2 . The duplex stainless steel material according to  claim 1 , wherein
 the chemical composition contains one or more types of elements selected from the 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%, and   Hf: 0.001 to 0.100%.   
     
     
         3 . The duplex stainless steel material according to  claim 1 , wherein
 the chemical composition contains one or more types of elements selected from the group consisting of:   B: 0.0005 to 0.0200%, and   rare earth metal: 0.001 to 0.200%.   
     
     
         4 . The duplex stainless steel material according to  claim 2 , wherein
 the chemical composition contains one or more types of elements selected from the group consisting of:   B: 0.0005 to 0.0200%, and   rare earth metal: 0.001 to 0.200%.

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