Grain refined tin brass

Abstract

There is provided a tin brass alloy having a grain structure that is refined by the addition of controlled amounts of both zinc and iron. Other metallic elements that undergo peritectic decomposition in a tin brass alloy, such as cobalt, iridium, niobium, vanadium and molybdenum may substitute for from a portion to all of the iron. Direct chill cast alloys containing from 1% to 4%, by weight of tin, from 0.8% to 4% of iron, from an amount effective to enhance iron initiated grain refinement to 20% of zinc and the remainder copper and inevitable impurities are readily hot worked. The zinc addition further increases the strength of the alloy and improves the bend formability in the “good way”, perpendicular to the longitudinal axis of a rolled strip.

We claim:  
     
         1 . A copper alloy, consisting essentially of: 
 from 1% to 4% by weight of tin;    from an amount effective to enhance peritectic initiated grain refinement to 20% by weight of zinc;    up to 0.4% by weight of phosphorous;    a combination of iron and cobalt present in an amount satisfying the equation:    Fe+ M Co=0.8%-4.0% by weight;    where M is between 0.45 and 0.65; and    the remainder copper and inevitable impurities, said alloy having a refined as-cast average crystalline grain size of less than 100 microns.    
     
     
         2 . The copper alloy of    claim 1    wherein said zinc is present in an amount of from 5% to 15% by weight.  
     
     
         3 . The copper alloy of    claim 2    wherein said zinc is present in an amount of from 8% to 12% by weight.  
     
     
         4 . The copper alloy of    claim 3    wherein a portion of said zinc is replaced at a 1:1 atomic ratio with an element selected from the group consisting of aluminum, manganese and mixtures thereof.  
     
     
         5 . The copper alloy of    claim 2    wherein Fe+MCo=1.6%-2.2%  
     
     
         6 . The copper alloy of    claim 5    wherein Fe+MCo=1.6%-1.8%.  
     
     
         7 . The copper alloy of    claim 2    wherein a portion of said iron+cobalt is replaced with one or more peritectic reaction initiators selected from the group consisting of iridium, niobium, vanadium and molybdenum.  
     
     
         8 . The copper alloy of    claim 5    wherein a portion of said zinc is replaced at a 1:1 atomic ratio with an element selected from the group consisting of aluminum, manganese and mixtures thereof.  
     
     
         9 . The copper alloy of    claim 6    wherein said tin content is from 1.2% to 2.2%.  
     
     
         10 . The copper alloy of    claim 9    wherein said phosphorous content is from 0.03% to 0.3%.  
     
     
         11 . The copper alloy of    claim 9    further containing an addition selected from the group consisting of nickel, magnesium, beryllium, silicon, zirconium, titanium, chromium and mixtures thereof, wherein each component of said addition is present in an amount of less than 0.4% by weight.  
     
     
         12 . The copper alloy of    claim 9    being wrought to a thickness of from 0.005 inch to 0.015 inch and having an average final gauge grain size of from 3 microns to 20 microns.  
     
     
         13 . An electrical connector formed from the alloy of    claim 9   .  
     
     
         14 . A spring formed from the alloy of    claim 12   .  
     
     
         15 . A copper alloy, consisting essentially of: 
 from 1% to 4% by weight of tin;    a peritectic reaction initiator selected in an amount effective to provide said copper alloy with a fine grain microstructure without an excessive degradation in electrical conductivity and strength selected from the group consisting of cobalt, iridium, vanadium, molybdenum and mixtures thereof;    from an amount effective to enhance peritectic initiated grain refinement to 20% by weight of zinc;    up to 0.4% by weight of phosphorous; and    the remainder copper and inevitable impurities, said alloy having a refined as-cast average crystalline grain size of less than 100 microns.    
     
     
         16 . The copper alloy of    claim 15    wherein said peritectic reaction initiator is cobalt present in an amount of from about 3.2% to about 4.4%  
     
     
         17 . The copper alloy of    claim 15    wherein said peritectic reaction initiator is iridium present in an amount of from about 10% to about 20%  
     
     
         18 . The copper alloy of    claim 15    wherein said peritectic reaction initiator is niobium present in an amount of from about 0.01% to about 5%  
     
     
         19 . The copper alloy of    claim 15    wherein said peritectic reaction initiator is vanadium present in an amount of from about 0.01% to about 5%  
     
     
         20 . The copper alloy of    claim 15    wherein said peritectic reaction initiator is molybdenum present in an amount of from about 0.5% to about 5%