Low lead alloy

Abstract

A composition for a low lead ingot comprising primarily copper and including tin, zinc, sulfur, phosphorus, nickel. The composition may contain carbon. The low lead ingot, when solidified, includes sulfur or sulfur containing compounds such as sulfides distributed through the ingot. The presence and a substantially uniform distribution of these sulfur compounds imparts improved machinability and better mechanical properties.

What is claimed is: 
     
         1 . An alloy composition consisting essentially of:
 a copper content of 82 wt % to 89 wt %;   a tin content of 2.0 wt % to 4.0 wt %;   a lead content of less than 0.09 wt %;   a zinc content of 5.0 wt % to 14.0 wt %;   an iron content of 0.4 wt % or less but greater than 0 wt %;   an antimony content of 0.02 wt % or less but greater than 0 wt %;   a nickel content of 0.5 wt % to 2.0 wt %;   a sulfur content of 0.01 wt % to 0.65 wt %;   a phosphorus content of 0.05 wt % or less but greater than 0 wt %;   an aluminum content of 0.005 wt % or less but greater than 0 wt %;   a silicon content of 0.005 wt % or less but greater than 0 wt %;   a manganese content of 0.01% to 0.7 wt %;   one or more of a zirconium content of 0.2 wt % or less but greater than 0 wt % and a boron content of 0.2 wt % or less but greater than 0 wt %;   a carbon content of up to 0.1%; and   a titanium content of up to 0.3%.   
     
     
         2 . The alloy composition of  claim 1 , further wherein the iron content is 0.4 wt %. 
     
     
         3 . The alloy composition of  claim 2 , further wherein the antimony content is 0.02 wt %. 
     
     
         4 . The alloy composition of  claim 3 , further wherein the phosphorous content is 0.05 wt %. 
     
     
         5 . The alloy composition of  claim 4 , further wherein the aluminum content is 0.005 wt %. 
     
     
         6 . The alloy composition of  claim 5 , further wherein the silicon content is 0.005 wt %. 
     
     
         7 . The alloy composition of  claim 6 , further wherein the zirconium content is 0.2 wt %. 
     
     
         8 . The alloy composition of  claim 7 , further wherein the boron content is 0.2 wt %. 
     
     
         9 . The alloy composition of  claim 8 , further wherein the carbon content is 0.1 wt %. 
     
     
         10 . The alloy composition of  claim 9 , further wherein the titanium content is 0.3 wt %. 
     
     
         11 . An alloy composition consisting essentially of:
 a copper content of 82 wt % to 89 wt %;   a tin content of 2.0 wt % to 4.0 wt %;   a lead content of 0.09 wt % or less;   a zinc content of 5.0 wt % to 14.0 wt %;   an iron content than 0.4 wt % or less;   an antimony content of 0.02 wt %;   a nickel content of 0.5 wt % to 2.0 wt %;   a sulfur content of 0.1 wt % to 0.65 wt %;   a phosphorus content of 0.05 wt % or less but greater than 0 wt %;   an aluminum content of 0.005 wt %;   a silicon content of 0.005 wt % or less;   a manganese content of 0.01% to 0.7 wt %;   a zirconium content of 0.2 wt % or less but greater than 0 wt %; and   a boron content of 0.2 wt % or less but greater than 0 wt %.   
     
     
         12 . The alloy composition of  claim 11 , further wherein the iron content is 0.4 wt %. 
     
     
         13 . The alloy composition of  claim 12 , further wherein the antimony content is 0.02 wt %. 
     
     
         14 . A method for producing a copper alloy of  claim 1 , comprising:
 heating a base ingot in the vessel to a temperature of about 1,149 degrees Celsius to form a melt;   ceasing heating of the melt and plunging one or more additives containing, tin, zinc, nickel and carbon, into the melt;   skimming at least a partial amount of slag from the melt;   heating the melt to a temperature of about 1,171 Celsius;   ceasing heating of the melt and plunging sulfur into the melt;   heating the melt to a temperature of about 1,177 degrees Celsius; and   removing slag from the melt;   forming the copper alloy comprising:
 a copper content of about 82% to about 89%, 
 a sulfur content of about 0.01% to about 0.65%; 
 a tin content of about 2.0% to about 4.0%; 
 a lead content of less than about 0.09%; 
 a zinc content of about 5.0% to about 14.0%; 
 a carbon content of about 0.1%; and 
 a nickel content of about 0.5% to about 2.0%. 
   
     
     
         15 . The method of  claim 14 , further comprising, prior to heating the base ingot, adding carbon to the vessel wherein the carbon comprises graphite. 
     
     
         16 . The method of  claim 14 , wherein the carbon comprises calcinated petroleum coke or copper coated graphite. 
     
     
         17 . The method of  claim 14 , wherein the one or more additives containing carbon comprise carbon wrapped in copper foil which had been preheated to at least 150° C. to remove moisture. 
     
     
         18 . The method of  claim 14 , wherein the crucible is heated using an induction furnace and wherein the melt undergoes inductive stirring. 
     
     
         19 . The method of  claim 14 , wherein plunging one or more additives occurs over between 15 to 20 seconds. 
     
     
         20 . The method of  claim 14 , further comprising plunging phosphorus into the melt after the plunging of the sulfur.