High-nitrogen austenitic stainless steel

Abstract

A high-nitrogen austenitic stainless steel, containing 0.005 mass %≦C≦0.25 mass %; 15.0 mass %≦Cr≦35.0 mass %; 0.2 mass %<Mn<10.0 mass %; 0.05 mass %≦Mo≦8.0 mass %; 0.01 mass %≦Cu≦4.0 mass %; 0.01 mass %≦Ni<5.0 mass %; 0.8 mass %<N≦1.8 mass %; Si≦2.0 mass %; P≦0.03 mass %; S≦0.05 mass %; Al≦0.030 mass %; 0≦0.020 mass %, and the balance substantially including Fe and impurities, and having a PRE (=(Cr+3.3Mo+16N)/Mn (mass %)) of not less than 5 and a CRE (=Cr+1.5Mo+2N+Cu (mass %)) of not less than 27.

1 . A high-nitrogen austenitic stainless steel, comprising: 
 0.005 mass %≦C≦0.25 mass %;    15.0 mass %≦Cr≦35.0 mass %;    0.2 mass %<Mn<10.0 mass %;    0.05 mass %≦Mo≦8.0 mass %;    0.01 mass %≦Cu≦4.0 mass %;    0.01 mass %≦Ni<5.0 mass %;    0.8 mass %<N≦1.8 mass %;    Si≦2.0 mass %;    P≦0.03 mass %;    S≦0.05 mass %;    Al≦0.030 mass %;    O≦0.020 mass %, and having:    PRE represented by an equation (1) and of not less than 5,       PRE=(Cr+ 3.3Mo+16N)/Mn(mass %)  (1)   and    CRE represented by an equation (2) and of not less than 27,       CRE=Cr+ 1.5Mo+2N+Cu(mass %)  (2)   and    further optionally containing one or more elements selected from the group consisting of:    at least one of: 
 0.01 mass %≦W≦8.0 mass %; and  
 0.01 mass %≦Co≦5.0 mass %;  
   at least one of: 
 0.01 mass %≦Ti≦0.5 mass %;  
 0.01 mass %≦Nb≦0.5 mass %;  
 0.01 mass %≦V<1.0 mass %;  
 0.01 mass %≦Ta≦0.5 mass %; and  
 0.01 mass %≦Zr≦0.5 mass %;  
   at least one of: 
 0.001 mass %≦B≦0.01 mass %;  
 0.001 mass %≦Ca≦0.01 mass %; and  
 0.001 mass %≦Mg≦0.01 mass %;  
   at least one of: 
 0.005 mass %≦Te≦0.05 mass %; and  
 0.01 mass %≦Se≦0.20 mass %; and  
   the balance substantially containing Fe and impurities.    
   
   
       2 . The high-nitrogen austenitic stainless steel according to  claim 1 , wherein an index of stability of austenite phase: Ni eq −Cr eq  is not less than 0, wherein 
       Ni eq =Ni+Co+0.5Mn+0.3Cu+25N+30C Cr eq =Cr+2Si+1.5Mo+5V+5.5Al+1.75Nb+1.5Ti+0.75W. 
   
   
       3 . The high-nitrogen austenitic stainless steel according to  claim 1  or  2 , wherein tensile strength in a solution-treated state is not less than 1000 MPa.  
   
   
       4 . The high-nitrogen austenitic stainless steel according to  claim 1  or  2 , wherein tensile strength after solution treatment and cold working is not less than 1800 MPa.  
   
   
       5 . The high-nitrogen austenitic stainless steel according to  claim 1  or  2 , wherein tensile strength after solution treatment and cold working is not less than 2000 MPa, and elongation is not less than 10%.  
   
   
       6 . The high-nitrogen austenitic stainless steel according to  claim 3 , wherein tensile strength after solution treatment and cold working is not less than 1800 MPa.  
   
   
       7 . The high-nitrogen austenitic stainless steel according to  claim 3 , wherein tensile strength after solution treatment and cold working is not less than 2000 MPa, and elongation is not less than 10%.  
   
   
       8 . The high-nitrogen austenitic stainless steel according to  claim 4 , wherein tensile strength after solution treatment and cold working is not less than 2000 MPa, and elongation is not less than 10%.  
   
   
       9 . The high-nitrogen austenitic stainless steel according to  claim 6 , wherein tensile strength after solution treatment and cold working is not less than 2000 MPa, and elongation is not less than 10%.