Martensitic stainless steel

Abstract

A martensitic stainless steel of this invention, aimed at achieving excellent corrosion resistance and cold workability and a desirable level of toughness, while keeping the hardness equivalent to that of conventional martensitic stainless steel, which consists essentially of, in % by mass, C: less than 0.15%, Si: 0.05% or more and less than 0.20%, Mn: 0.05-2.0%, P: 0.03% or less, S: 0.03% or less, Cu: 0.05-3.0%, Ni: 0.05-3.0%, Cr: 13.0-20.0%, Mo: 0.2-4.0%, V: 0.01-1.0%, Al: 0.030% or less, Ti: less than 0.020%, O: 0.020% or less, N: 0.40-0.80%, and the balance of Fe and inevitable impurities.

1 . A martensitic stainless steel consisting essentially of, in % by mass, C: less than 0.15%, Si: 0.05% or more and less than 0.20%, Mn: 0.05-2.0%, P: 0.03% or less, S: 0.03% or less, Cu: 0.05-3.0%, Ni: 0.05-3.0%, Cr: 13.0-20.0%, Mo: 0.2-4.0%, V: 0.01-1.0%, Al: 0.030% or less, Ti: less than 0.020%, O: 0.020% or less, N: 0.40-0.80%, and the balance of Fe and inevitable impurities.  
     
     
         2 . The martensitic stainless steel as claimed in  claim 1 , further containing any one or more of steel components which consist of Co: 0.05-4.0%, W: 0.020-0.20%, Ta: 0.020-0.20%, and Nb: 0.010-0.20%.  
     
     
         3 . The martensitic stainless steel as claimed in  claim 1 , further containing any one or more of steel components which consist of B: 0.001-0.01%, Mg: 0.001-0.01%, Ca: 0.001-0.01%, and Zr: 0.020-0.20%.  
     
     
         4 . The martensitic stainless steel as claimed in  claim 2 , further containing any one or more of steel components which consist of B: 0.001-0.01%, Mg: 0.001-0.01%, Ca: 0.001-0.01%, and Zr: 0.020-0.20%.  
     
     
         5 . The martensitic stainless steel as claimed in  claim 1 , further containing any one of or both of steel components which consist of Te: 0.005-0.05% and Se: 0.02-0.20%.  
     
     
         6 . The martensitic stainless steel as claimed in  claim 2 , further containing any one of or both of steel components which consist of Te: 0.005-0.05% and Se: 0.02-0.20%.  
     
     
         7 . The martensitic stainless steel as claimed in  claim 3 , further containing any one of or both of steel components which consist of Te: 0.005-0.05% and Se: 0.02-0.20%.  
     
     
         8 . The martensitic stainless steel as claimed in  claim 4 , further containing any one of or both of steel components which consist of Te: 0.005-0.05% and Se: 0.02-0.20%.  
     
     
         9 . The martensitic stainless steel as claimed in  claim 1 , having a value of W C /W N  of less than 0.30, where W C  (%) is C content, and W N  (%) is N content.  
     
     
         10 . The martensitic stainless steel as claimed in  claim 2 , having a value of W C /W N  of less than 0.30, where W C  (%) is C content, and W N  (%) is N content.  
     
     
         11 . The martensitic stainless steel as claimed in  claim 3 , having a value of W C /W N  of less than 0.30, where W C  (%) is C content, and W N  (%) is N content.  
     
     
         12 . The martensitic stainless steel as claimed in  claim 4 , having a value of W C /W N  of less than 0.30, where W C  (%) is C content, and W N  (%) is N content.  
     
     
         13 . The martensitic stainless steel as claimed in  claim 5 , having a value of W C /W N  of less than 0.30, where W C  (%) is C content, and W N  (%) is N content.  
     
     
         14 . The martensitic stainless steel as claimed in  claim 6 , having a value of W C /W N  of less than 0.30, where W C  (%) is C content, and W N  (%) is N content.  
     
     
         15 . The martensitic stainless steel as claimed in  claim 7 , having a value of W C /W N  of less than 0.30, where W C  (%) is C content, and W N  (%) is N content.  
     
     
         16 . The martensitic stainless steel as claimed in  claim 8 , having a value of W C /W N  of less than 0.30, where W C  (%) is C content, and W N  (%) is N content.  
     
     
         17 . The martensitic stainless steel as claimed in  claim 1 , having a mean crystal grain size of the prior austenitic grain in the tempered martensitic structure of 50 μm or less.  
     
     
         18 . The martensitic stainless steel as claimed in  claim 2 , having a mean crystal grain size of the prior austenitic grain in the tempered martensitic structure of 50 μm or less.  
     
     
         19 . The martensitic stainless steel as claimed in  claim 3 , having a mean crystal grain size of the prior austenitic grain in the tempered martensitic structure of 50 μm or less.  
     
     
         20 . The martensitic stainless steel as claimed in  claim 4 , having a mean crystal grain size of the prior austenitic grain in the tempered martensitic structure of 50 μm or less.  
     
     
         21 . The martensitic stainless steel as claimed in  claim 5 , having a mean crystal grain size of the prior austenitic grain in the tempered martensitic structure of 50 μm or less.  
     
     
         22 . The martensitic stainless steel as claimed in  claim 6 , having a mean crystal grain size of the prior austenitic grain in the tempered martensitic structure of 50 μm or less.  
     
     
         23 . The martensitic stainless steel as claimed in  claim 7 , having a mean crystal grain size of the prior austenitic grain in the tempered martensitic structure of 50 μm or less.  
     
     
         24 . The martensitic stainless steel as claimed in  claim 8 , having a mean crystal grain size of the prior austenitic grain in the tempered martensitic structure of 50 μm or less.  
     
     
         25 . The martensitic stainless steel as claimed in  claim 9 , having a mean crystal grain size of the prior austenitic grain in the tempered martensitic structure of 50 μm or less.  
     
     
         26 . The martensitic stainless steel as claimed in  claim 10 , having a mean crystal grain size of the prior austenitic grain in the tempered martensitic structure of 50 μm or less.  
     
     
         27 . The martensitic stainless steel as claimed in  claim 11 , having a mean crystal grain size of the prior austenitic grain in the tempered martensitic structure of 50 μm or less.  
     
     
         28 . The martensitic stainless steel as claimed in  claim 12 , having a mean crystal grain size of the prior austenitic grain in the tempered martensitic structure of 50 μm or less.  
     
     
         29 . The martensitic stainless steel as claimed in  claim 13 , having a mean crystal grain size of the prior austenitic grain in the tempered martensitic structure of 50 μm or less.  
     
     
         30 . The martensitic stainless steel as claimed in  claim 14 , having a mean crystal grain size of the prior austenitic grain in the tempered martensitic structure of 50 μm or less.  
     
     
         31 . The martensitic stainless steel as claimed in  claim 15 , having a mean crystal grain size of the prior austenitic grain in the tempered martensitic structure of 50 μm or less.  
     
     
         32 . The martensitic stainless steel as claimed in  claim 16 , having a mean crystal grain size of the prior austenitic grain in the tempered martensitic structure of 50 μm or less.