Method and apparatus for making high strength metals with a face-centered-cubic structure

Abstract

A process for increasing the strength of pure copper and other fcc matrix alloys while maintaining ductility. The method is particularly applicable to face-centered-cubic materials that undergo dynamic recovery when strain-hardened at room temperature. The material is first subjected to equal channel angular pressing to create an ultra fine grain structure (“UFG”). The UFG sample is then subjected to cryogenic drawing and finally to subcryogenic deformation.

1 . A method for strain hardening a length of metal having a longitudinal axis while reducing dynamic recovery, maintaining ductility and electrical conductivity, comprising:
 a. passing said length of metal through an equal channel angular pressing die for a number of passes sufficient to transition said metal to an ultra fine grained structure;   b. providing a drawing or extrusion die, located within a vessel and immersed in a cryogenic liquefied gas;   c. passing said length of metal through said drawing/extrusion die while a portion of said length of metal proximate said drawing die and said drawing die remain immersed in said cryogenic liquefied gas;   d. providing a rolling die; and   e. passing said length of metal through said rolling die while a portion of said length of metal precooled with cryogenic liquefied gas.   
     
     
         2 . A method of strain hardening as recited in  claim 1 , wherein said cryogenic liquefied gas is liquid nitrogen. 
     
     
         3 . A method of strain hardening as recited in  claim 1  wherein said length of metal is rotated 90 degrees about said longitudinal axis between each successive pass through said equal channel angular pressing die. 
     
     
         4 . A method of strain hardening as recited in  claim 1 , wherein said length of metal is fed into said drawing die from a payoff reel, through said drawing die, and onto a draw reel. 
     
     
         5 . A method of strain hardening as recited in  claim 4 , wherein said payoff reel is contained within said vessel and said draw reel is located outside said vessel. 
     
     
         6 . A method of strain hardening as recited in  claim 4 , wherein both said payoff reel and said draw reel are located outside said vessel. 
     
     
         7 . A method of strain hardening as recited in  claim 6 , wherein said wire is fed from said payoff reel to a first idler pulley, then through said drawing die, then to a second idler pulley, and then to said draw reel. 
     
     
         8 . A method of strain hardening as recited in  claim 7 , wherein said first and second idler pulleys are contained within said vessel. 
     
     
         9 . A method for strain hardening a length of metal having a longitudinal axis while reducing dynamic recovery and maintaining ductility, comprising:
 a. providing a volume of cryogenic liquefied gas;   b. providing a drawing or extrusion die;   c. providing a rolling die;   d. immersing said drawing die and said deformation die in said volume of cryogenic liquefied gas;   e. passing said length of metal through an equal channel angular pressing die for a number of passes sufficient to transition said metal to an ultra fine grained structure;   f. thereafter passing said length of metal through said rolling die while immersed in said volume of cryogenic liquefied gas; and   g. thereafter passing said length of metal through said rolling die while said metal is precooled by cryogenic liquefied gas   
     
     
         10 . A method of strain hardening as recited in  claim 9 , wherein said cryogenic liquefied gas is liquid nitrogen. 
     
     
         11 . A method of strain hardening as recited in  claim 9  wherein said length of metal is rotated 90 degrees about said longitudinal axis between each successive pass through said equal channel angular pressing die. 
     
     
         12 . A method of strain hardening as recited in  claim 9 , wherein said length of metal is fed into said drawing die from a payoff reel, through said drawing die, and onto a draw reel. 
     
     
         13 . A method of strain hardening as recited in  claim 12 , wherein said payoff reel is contained within said vessel and said draw reel is located outside said vessel. 
     
     
         14 . A method of strain hardening as recited in  claim 13 , wherein both said payoff reel and said draw reel are located outside said vessel. 
     
     
         15 . A method of strain hardening as recited in  claim 14 , wherein said wire is fed from said payoff reel to a first idler pulley, then through said drawing die, then to a second idler pulley, and then to said draw reel. 
     
     
         16 . A method of strain hardening as recited in  claim 15 , wherein said first and second idler pulleys are contained within said vessel. 
     
     
         17 . A method of strain hardening as recited in  claim 3 , wherein said cryogenic liquefied gas is liquid nitrogen. 
     
     
         18 . A method of strain hardening as recited in  claim 4 , wherein said cryogenic liquefied gas is liquid nitrogen. 
     
     
         19 . A method of strain hardening as recited in  claim 5 , wherein said cryogenic liquefied gas is liquid nitrogen. 
     
     
         20 . A method of strain hardening as recited in  claim 6 , wherein said cryogenic liquefied gas is liquid nitrogen.