Processes for producing articles with stress-free slit edges

Abstract

Processes for producing articles with stress-free edges which comprise slitting a copper or copper alloy sheet to provide strips of the copper material, heating the strips in a furnace at a temperature of 200-250° C. under a protective atmosphere, and cooling the strips to room temperature, the strips so produced being useful to make stamped articles.

What is claimed is:  
     
         1 . A process for producing articles with stress-free slit edges, which method comprises slitting a copper-based sheet to produce strips of the copper-based material, heating the strips in a furnace under a protective atmosphere at a temperature of from about 200° C. to about 250° C. for a period of time to free the strip of stresses, and cooling the strips to room temperature.  
     
     
         2 . A process according to  claim 1  wherein the copper-based sheet is copper or a copper alloy.  
     
     
         3 . A process according to  claim 2  wherein the alloy is an alloy of copper and zinc or an alloy of copper and tin.  
     
     
         4 . A process according to  claim 1  wherein the temperature is from about 200° C. to about 240° C.  
     
     
         5 . A process according to  claim 1  wherein the heating is carried out for from one hour to ten hours.  
     
     
         6 . A process according to  claim 1  wherein the heating is carried out for from about four hours to about eight hours.  
     
     
         7 . A process according to  claim 1  wherein the protective atmosphere comprises an inert gas.  
     
     
         8 . A process according to  claim 1  wherein the protective atmosphere comprises nitrogen.  
     
     
         9 . A process according to  claim 1  wherein the protective atmosphere is a reducing atmosphere.  
     
     
         10 . A process according to  claim 9  wherein the atmosphere contains from about one to about 30 percent by volume of hydrogen.  
     
     
         11 . A process according to  claim 10  wherein the protective atmosphere contains from 70 to 99 percent by volume of nitrogen and the remainder of the atmosphere is hydrogen.  
     
     
         12 . A process according to  claim 1  wherein the width of the strips is from about one-quarter inch to four inches.  
     
     
         13 . A process according to  claim 1  wherein the width of the strips is from one to two inches.  
     
     
         14 . A process according to  claim 1  wherein the sheet thickness is from 0.010 to 0.020 inches.  
     
     
         15 . An article prepared according to  claim 1 .  
     
     
         16 . A copper strip that has been annealed under a protective atmosphere at a temperature between about 200° C. and 250° C. for one to ten hours and then stamped or cut into a desired shape, the copper strip after annealing stamping being essentially free of camber or twist.