Corrosion-Resistant, Free-Machining, Magnetic Stainless Steel

Abstract

A corrosion-resistant, free-machining, magnetic stainless steel alloy is described. The alloy has the following weight percent composition: 0.025 max. C, 0.60 max. Mn, 1.0-2.0 Si, 0.035 max. P, 0.15-0.40 S, 12.0-14.0 Cr, 0.5 max. Ni, 0.5-1.3 Mo, 0.5-1.3 V, 0.5 max. Cu, 0.020 max. Al, 0.025 max. N, and the balance is iron and usual impurities.

1 . A corrosion-resistant, free-machining, magnetic stainless steel alloy consisting essentially of, in weight percent 
     
       
         
               
               
               
               
             
                   
                   
               
                   
                 C 
                 0.025 
                 max 
               
                   
                 Mn 
                 0.60 
                 max 
               
               
               
               
             
                   
                 Si 
                 1.2-2.0 
               
               
               
               
               
             
                   
                 P 
                 0.035 
                 max 
               
               
               
               
             
                   
                 S 
                 0.15-0.40 
               
                   
                 Cr 
                 12.0-14.0 
               
               
               
               
               
             
                   
                 Ni 
                 0.5 
                 max 
               
               
               
               
             
                   
                 Mo 
                 0.5-1.3 
               
                   
                 V 
                 0.5-1.3 
               
               
               
               
               
             
                   
                 Cu 
                 0.5 
                 max 
               
                   
                 Al 
                 0.020 
                 max 
               
                   
                 N 
                 0.025 
                 max 
               
                   
                   
               
           
              
             
             
              
              
             
          
           
              
             
          
           
              
             
          
           
              
              
             
          
           
              
             
          
           
              
              
             
          
           
              
              
              
              
             
          
         
       
       and the balance iron and usual impurities. 
     
   
   
       2 . A corrosion-resistant, free-machining, magnetic stainless steel alloy as claimed in  claim 1  which contains at least about 0.8% vanadium. 
   
   
       3 . A corrosion-resistant, free-machining, magnetic stainless steel alloy as claimed in  claim 2  which contains at least about 0.8% molybdenum. 
   
   
       4 . A corrosion-resistant, free-machining, magnetic stainless steel alloy as claimed in  claim 1  which contains not more than about 13.5% chromium. 
   
   
       5 . A corrosion-resistant, free-machining, magnetic stainless steel alloy as claimed in  claim 4  which contains at least about 12.5% chromium. 
   
   
       6 . A corrosion-resistant, free-machining, magnetic stainless steel alloy as claimed in  claim 1  which contains not more than about 0.020% carbon. 
   
   
       7 . A corrosion-resistant, free-machining, magnetic stainless steel alloy as claimed in  claim 6  which contains not more than about 0.020% nitrogen. 
   
   
       8 . A corrosion-resistant, free-machining, magnetic stainless steel alloy as claimed in  claim 1  which contains not more than about 0.010% aluminum. 
   
   
       9 . A corrosion-resistant, free-machining, magnetic stainless steel alloy as claimed in  claim 1  which contains not more than about 0.50% manganese. 
   
   
       10 . A corrosion-resistant, free-machining, magnetic stainless steel alloy as claimed in  claim 1  which contains at least about 0.20% sulfur. 
   
   
       11 . A corrosion-resistant, free-machining, magnetic stainless steel alloy as claimed in  claim 1  which contains not more than about 0.35% sulfur. 
   
   
       12 . A corrosion-resistant, free-machining, magnetic stainless steel alloy as claimed in  claim 1  which contains not more than about 0.4% nickel. 
   
   
       13 . A corrosion-resistant, free-machining, magnetic stainless steel alloy as claimed in  claim 1  which contains not more than about 0.4% copper. 
   
   
       14 . A corrosion-resistant, free-machining, magnetic stainless steel alloy as claimed in  claim 1  which contains at least about 0.8% vanadium and at least about 0.8% molybdenum. 
   
   
       15 . A corrosion-resistant, free-machining, magnetic stainless steel alloy as claimed in  claim 14  which contains not more than about 0.4% nickel and not more than about 0.4% copper. 
   
   
       16 . A corrosion-resistant, free-machining, magnetic stainless steel alloy as claimed in  claim 14  which contains not more than about 0.010% aluminum. 
   
   
       17 . A corrosion-resistant, free-machining, magnetic stainless steel alloy consisting essentially of, in weight percent 
     
       
         
               
               
               
               
             
                   
                   
               
                   
                 C 
                 0.020 
                 max 
               
                   
                 Mn 
                 0.50 
                 max 
               
               
               
               
             
                   
                 Si 
                 1.2-1.8 
               
               
               
               
               
             
                   
                 P 
                 0.025 
                 max 
               
               
               
               
             
                   
                 S 
                 0.20-0.35 
               
                   
                 Cr 
                 12.5-13.5 
               
               
               
               
               
             
                   
                 Ni 
                 0.4 
                 max 
               
               
               
               
             
                   
                 Mo 
                 0.5-1.2 
               
                   
                 V 
                 0.5-1.2 
               
               
               
               
               
             
                   
                 Cu 
                 0.4 
                 max 
               
                   
                 Al 
                 0.010 
                 max 
               
                   
                 N 
                 0.020 
                 max 
               
                   
                   
               
           
              
             
             
              
              
             
          
           
              
             
          
           
              
             
          
           
              
              
             
          
           
              
             
          
           
              
              
             
          
           
              
              
              
              
             
          
         
       
       and the balance iron and usual impurities. 
     
   
   
       18 . A free-machining article formed from an alloy comprising, in weight percent, about 
     
       
         
               
               
               
               
             
                   
                   
               
                   
                 C 
                 0.025 
                 max 
               
                   
                 Mn 
                 0.60 
                 max 
               
               
               
               
             
                   
                 Si 
                 1.2-2.0 
               
               
               
               
               
             
                   
                 P 
                 0.035 
                 max 
               
               
               
               
             
                   
                 S 
                 0.15-0.40 
               
                   
                 Cr 
                 12.0-14.0 
               
               
               
               
               
             
                   
                 Ni 
                 0.5 
                 max 
               
               
               
               
             
                   
                 Mo 
                 0.5-1.3 
               
                   
                 V 
                 0.5-1.3 
               
               
               
               
               
             
                   
                 Cu 
                 0.5 
                 max 
               
                   
                 Al 
                 0.020 
                 max 
               
                   
                 N 
                 0.025 
                 max 
               
                   
                   
               
           
              
             
             
              
              
             
          
           
              
             
          
           
              
             
          
           
              
              
             
          
           
              
             
          
           
              
              
             
          
           
              
              
              
              
             
          
         
       
       and the balance iron and usual impurities;
 said article providing corrosion-resistance and reduced coercivity in the cold-worked and annealed condition. 
 
     
   
   
       19 . An article as claimed in  claim 18  which has a finished size formed by a single cold reduction step comprising about a 10-25% reduction in cross-sectional area. 
   
   
       20 . An article as claimed in  claim 19  which has been annealed at about 700° C. to about 900° C. for at least about two hours and then cooled to room temperature.