Fe-Co-Ni alloy and use for the manufacture of a shadow mask

Abstract

Fe—Ni—Co alloy whose chemical composition contains, by weight: 32%≦Ni≦34%, 3.5%≦Co≦6.5%, 0%≦Mn≦0.1%, 0%≦Si≦0.1%≦0%≦Cr≦0.1%, 0.005%≦C≦0.02%, S≦0.001%, 0.0001%≦Ca≦0.002%, 0.0001%≦Mg≦0.002%, the substantial remainder preferably being iron and impurities resulting from smelting; the chemical composition of the alloy furthermore satisfying the relationships: Co+Ni≦38.5%, Co+0.5×Ni≧20%, Co+5×Ni≧165.5% and S≦0.02≦Mn+0.8×Ca+0.6×Mg. Use of the alloy for the manufacture of a shadow mask for a display cathode ray tube.

What is claimed as new and desired to be secured by Letters Patent of the United States is:  
     
         1 . An Fe—Ni—Co alloy whose chemical composition comprises, by weight based on total weight:  
       32%≦Ni≦34% 
       3.5%≦Co≦6.5% 
       0%≦Mn≦0.1% 
         
       0%≦Si≦0.1% 
         
       0%≦Cr≦0.1% 
       0.005%≦C≦0.02% 
       S≦0.001% 
       0.0001%≦Ca≦0.002% 
       0.0001%≦Mg≦0.002% 
       and further comprising iron and impurities resulting from smelting; the chemical composition of the alloy furthermore satisfying the relationships:  
       Co+Ni≦38.5% 
       Co+0.5×Ni≧20% 
       Co+5×Ni≧165.5% 
       and  
       S≦0.02≦Mn+0.8×Ca+0.6×Mg. 
     
     
         2 . The alloy as claimed in  claim 1 , wherein copper, molybdenum, vanadium and niobium contents are each present in less than 0.1%.  
     
     
         3 . The alloy as claimed in  claim 2 , wherein the sum of the weight percentages of manganese, silicon, chromium, copper, molybdenum, vanadium and niobium is less than, 0.3%.  
     
     
         4 . The alloy as claimed in  claim 1 , wherein the oxygen content is less than or equal to 0.01%, the nitrogen content is less than or equal to 0.005%, and the phosphorus content is less than or equal to 0.005%.  
     
     
         5 . The alloy as claimed in  claim 2 , wherein the oxygen content is less than or equal to 0.01%, the nitrogen content is less than or equal to 0.005%, and the phosphorus content is less than or equal to 0.005%.  
     
     
         6 . The alloy as claimed in  claim 3 , wherein the oxygen content is less than or equal to 0.01%, the nitrogen content is less than or equal to 0.005%, and the phosphorus content is less than or equal to 0.005%.  
     
     
         7 . A shadow mask, which comprises at least one foil drilled with holes, said foil comprising an alloy whose chemical composition comprises, by weight based on total weight:  
       32%≦Ni≦34% 
       3.5%≦Co≦6.5% 
       0%≦Mn≦0.1% 
       0%≦Si≦0.1% 
       0%≦Cr≦0.1% 
       0.005%≦C≦0.02% 
       S≦0.001% 
       0.0001%≦Ca≦0.002% 
       0.0001%≦Mg≦0.002% 
       and further comprising iron and impurities resulting from smelting; the chemical composition of the alloy furthermore satisfying the relationships:  
       Co+Ni≦38.5% 
       Co+0.5×Ni≧20% 
       Co+5×Ni≧165.5% 
       and  
       S≦0.02≦Mn+0.8×Ca+0.6×Mg. 
     
     
         8 . A method of forming a shadow mask, comprising drilling holes in a foil and drawing said drilled foil, wherein the foil comprises an alloy having a chemical composition which comprises, by weight based on total weight:  
       32%≦Ni≦34% 
       3.5%≦Co≦6.5% 
       0%≦Mn≦0.1% 
       0%≦Si≦0.1% 
       0%≦Cr≦0.1% 
       0.005%≦C≦0.02% 
       S≦0.001% 
       0.0001%≦Ca≦0.002% 
       0.0001%≦Mg≦0.002% 
       and further comprising iron and impurities resulting from smelting; the chemical composition of the alloy furthermore satisfying the relationships:  
       Co+Ni≦38.5% 
       Co+0.5×Ni≧20% 
       Co+5×Ni≧165.5% 
       and  
       S≦0.02×Mn+0.8×Ca+0.6×Mg.