Iron-nickel alloy having a low coefficient of expansion

Abstract

Iron/nickel alloy having a low coefficient of expansion, the chemical composition of which comprises iron, nickel, manganese, silicon, calcium, magnesium, less than 0.005% of aluminum, less than 0.001% of sulfur, less than 0.01% of oxygen, less than 0.005% of nitrogen, and less than 0.003% of phosphorus, the chemical composition furthermore satisfying the relationship: S ≦0.02×Mn+0.8×Ca+0.6×Mg

What is claimed as new and desired to be secured by Letters Patent of the United States is:  
     
         1 . An iron/nickel alloy having a coefficient of linear expansion less than 0.9×10 −6 /K and having a chemical composition which comprises iron and, by weight: 
 35.5%≦Ni≦37% 
 Mn≦0.1%  
 
 0.03%≦Si≦0.15%  
 0.0001%≦Ca≦0.002%  
 0.0001%≦Mg≦0.002% 
 Al≦0.005%  
 S≦0.001%  
 O≦0.01%  
 N≦0.005%  
 P≦0.003%  
 C≦0.005%  
 B≦0.0004%  
 H≦0.001%  
 Cr≦0.1%  
 Cu≦0.1%  
 Mo≦0.1%  
 V≦0.1%  
 Nb≦0.1%  
 Co≦0.5%,  
 wherein the chemical composition satisfys the following relation: 
   S≦ 0.02×Mn+0.8×Ca+0.6×Mg. 
 
 
     
     
         2 . The iron/nickel alloy as claimed in    claim 1   , wherein: 
 O≦0.005%    N≦0.003%    S≦0.0005%.    
     
     
         3 . The iron/nickel alloy as claimed in    claim 1   , wherein: 
       35.8%≦Ni≦36.3%. 
     
     
         4 . The iron/nickel alloy as claimed in    claim 3   , wherein: 
       35.9%≦Ni≦36.2%. 
     
     
         5 . The alloy as claimed in    claim 1   , wherein: 
       Cr+Cu+Mo+V+Nb+Si≦0.15%. 
     
     
         6 . The iron/nickel alloy as claimed in    claim 2   , wherein: 
       35.8%≦Ni≦36.3%. 
     
     
         7 . The alloy as claimed in    claim 2   , wherein: 
       Cr+Cu+Mo+V+Nb+Si≦0.15%. 
     
     
         8 . The alloy as claimed in    claim 3   , wherein: 
       Cr+Cu+Mo+V+Nb+Si≦0.15%. 
     
     
         9 . The alloy as claimed in    claim 4   , wherein: 
       Cr+Cu+Mo+V+Nb+Si≦0.15%. 
     
     
         10 . The iron/nickel alloy as claimed in    claim 1   , wherein said alloy is in the form of a strip and is obtained by hot rolling and then cold rolling the alloy, wherein a width of the strip is greater than 400 mm and a coefficient of expansion of the strip between 20° C. and 100° C. is less than 0.9×10 −6 /K.  
     
     
         11 . A shadow mask for a cathode ray tube comprising the alloy of    claim 1   .