Non-magnetic corrosion resistant high strength steels

Abstract

A non-magnetic corrosion and galling resistant high strength steel suitable for use as non-magnetic components in directional drilling of oil and gas wells whose composition by weight includes: carbon up to 0.2%; silicon up to 1.0%; manganese from 10.0 to 20.0%; chromium from 13.5 to 18.0%; nickel from 1.0 to 7.0%; molybdenum from 1.5 to 4.0%; and nitrogen from 0.2 to 0.4%, the composition satisfying the formulae: (i) and (ii): nickel equivalence+chromium equivalence>35.

1 . A non-magnetic corrosion and galling resistant high strength steel whose composition by weight includes  
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                     
                 
                     
                   Carbon 
                   up to 0.035% 
                 
                     
                   Silicon 
                   up to 0.5% 
                 
                     
                   Manganese 
                   from 13.0 to 15.0% 
                 
                     
                   Chromium 
                   from 15.0 to 16.0% 
                 
                     
                   Nickel 
                   from 2.0 to 2.75% 
                 
                     
                   Molybdenum 
                   from 2.0 to 2.5%; and 
                 
                     
                   Nitrogen 
                   from 0.30 to 0.40% 
                 
                     
                     
                 
                     
                     
                 
             
                
                
               
               
                
                
                
                
                
                
                
                
                
               
            
           
         
         balance iron and incidental impurities, the composition satisfying the formulae:  
         
           
             
               
                 
                   
                     
                       
                         
                           Nickel 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           equivalence 
                         
                         
                           Chromium 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           equivalence 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           minus 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           14 
                         
                       
                       > 
                       1.51 
                     
                   
                   
                     
                       ( 
                       i 
                       ) 
                     
                   
                 
                 
                   
                     and 
                   
                   
                     
                         
                     
                   
                 
                 
                   
                     
                       
                         
                           Nickel 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           equivalence 
                         
                         + 
                         
                           chromium 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           equivalence 
                         
                       
                       > 
                       35 
                     
                   
                   
                     
                       ( 
                       ii 
                       ) 
                     
                   
                 
               
             
           
         
       
     
     
         2 . A steel as claimed in  claim 1  wherein the composition further satisfies the formulae: 
         Cr equivalence+% Cr+1.5% Si+% Mo+0.12% Mn and Ni equivalence=% Ni+30%+20% N 
     
     
         3 . A steel as claimed in  claim 2  wherein the composition further satisfies the formulae: 
         Cr equivalence+% Cr+1.5% Si+% Mo; and Ni equivalence=% Ni+0.5% Mn+30% C+30% N. 
     
     
         4 . A non-magnetic component for use in directional drilling produced from a high strength corrosion resistant steel of composition as claimed in  claim 1 .  
     
     
         5 . A drill collar produced from a high strength corrosion resistant corrosion resistant steel as claimed in  claim 1 .  
     
     
         6 . A non-magnetic component for use in directional drilling produced from a high strength corrosion resistant steel of composition as claimed in  claim 2 .  
     
     
         7 . A non-magnetic component for use in directional drilling produced from a high strength corrosion resistant steel of composition as claimed in  claim 3 .  
     
     
         8 . A drill collar produced from a high strength corrosion resistant corrosion resistant steel as claimed in  claim 2 .  
     
     
         9 . A drill collar produced from a high strength corrosion resistant corrosion resistant steel as claimed in  claim 3.