Ferritic steel alloy

Abstract

Steel alloys include no more than 1.00 percent by weight of silicon, 18.0 to 22.0 percent by weight of chromium, 1.80 to 2.50 percent by weight of molybdenum, 0.01 to 0.10 percent by weight of nitrogen, no more than 0.01 percent by weight of titanium, no more than 0.01 percent by weight of niobium, no more than 0.01 percent by weight of aluminum, the remainder being essentially iron. The alloys are ferritic but polishable and have mechanical properties that nearly match those of the standard steel alloy no. 1.4521. The steel alloys are processed into watch parts such as housing bottoms, housing shells, and faces, among others, such that watch housings produced from the alloys magnetically shield the clockwork.

1 . A high-alloy ferritic steel alloy, comprising, based on the alloy, at the most 1.00 percent by weight silicon, 18.0 to 22.0 percent by weight chromium, 1.80 to 2.50 percent by weight molybdenum, 0.01 to 0.10 percent by weight nitrogen, at the most 0.01 percent by weight titanium, at the most 0.01 percent by weight niobium, at the most 0.01 percent by weight aluminum and as the remainder substantially iron.  
   
   
       2 . The steel alloy according to  claim 1 , comprising, based on the alloy, at the most 0.005 percent by weight titanium, at the most 0.005 percent by weight, at the most 0.005 percent by weight niobium, at the most 1.00 percent by weight manganese, at the most 0.04 percent by weight phosphorus and at the most 0.025 percent by weight carbon.  
   
   
       3 . The steel alloy as claimed in  claim 1 , comprising, based on the alloy, 19.5 to 20.5 percent by weight chromium, 1.90 to 2.10 percent by weight molybdenum and 0.05 to 0.10 percent by weight nitrogen.  
   
   
       4 . The steel alloy according to  claim 1 , comprising, based on the alloy, about 0.8 percent by weight silicon, about 20 percent by weight chromium, about 2 percent by weight molybdenum, about 0.05 percent by weight nitrogen and at the most 0.002 percent by weight titanium.  
   
   
       5 . The steel alloy according to  claim 1 , comprising, based on the alloy, at the most 0.10 percent by weight nickel.  
   
   
       6 . The steel alloy according to  claim 1 , comprising, based on the alloy, at the most 0.03 percent by weight sulphur.  
   
   
       7 . The steel alloy according to  claim 6 , comprising, based on the alloy, 0.015 to 0.03 percent by weight sulphur.  
   
   
       8 . A casing part for watches, consisting of a steel alloy according to  claim 1 .  
   
   
       9 . The casing part according to  claim 8 , in the form of a casing base or a casing shell.  
   
   
       10 . A watch face consisting of a steel alloy according to  claim 1 .  
   
   
       11 . A art for linked watch straps, consisting of a steel alloy according to  claim 1 .  
   
   
       12 . (canceled)  
   
   
       13 . A method for the production of a casing part for watches, comprising suspending a steel alloy in powder form according to  claim 1  in a liquid binder, introducing the suspension into a mould corresponding to the casing part, evaporating the binder, and sintering the powder residue in the mould and, if the alloy in powder form contains lower levels of nitrogen, sintering in a nitrogen-containing atmosphere.