Method for producing ultrafine-grained materials using repetitive corrugation and straightening

Abstract

A method of refining the grain structure and improving the hardness and strength properties of a metal or metal alloy workpiece is disclosed. The workpiece is subjected to forces that corrugate and then straighten the workpiece. These steps are repeated until an ultrafine-grained product having improved hardness and strength is produced.

What is claimed is:  
     
         1 . A method for producing an ultrafine-grained product, comprising the steps of: 
 (a) bending a metal or alloy workpiece having opposing, substantially flat surfaces into a corrugated shape;    (b) applying forces to the corrugated workpiece sufficient to substantially restore the flat surfaces and produce a finer-grained workpiece; and    (c) repeating steps (a) and (b) until the workpiece is transformed into an ultrafine-grained product having a refined grain size and improved strength.    
     
     
         2 . The method of  claim 1 , the process further comprising the step of annealing the workpiece after step (a).  
     
     
         3 . The method of  claim 1 , the process further comprising the step of annealing the workpiece after step (b).  
     
     
         4 . The method of  claim 1 , further comprising the step of lubricating the workpiece.  
     
     
         5 . The method of  claim 1 , further comprising the step of rotating the workpiece after performing step (a) and step (b) but before performing step (a) again.  
     
     
         6 . The method of  claim 1 , further comprising the step of warming the workpiece before performing step (a).  
     
     
         7 . The method of  claim 1 , further comprising the step of warming the workpiece before performing step (b).  
     
     
         8 . The method of  claim 1 , further comprising the step of cooling the workpiece before step (a).  
     
     
         9 . The method of  claim 1 , further comprising the step of cooling the workpiece during step (a).  
     
     
         10 . the method of  claim 1 , further comprising the step of cooling the workpiece prior to step (b).  
     
     
         11 . The method of  claim 1 , further comprising the step of cooling the workpiece during step (b).  
     
     
         12 . An ultrafine-grained metal or alloy product made by the process of: 
 (a) bending a metal or alloy workpiece having opposing, substantially flat surfaces into a corrugated shape;    (b) applying forces to the corrugated workpiece sufficient to substantially restore the flat surfaces and produce a finer-grained workpiece; and    (c) repeating steps (a) and (b) until the workpiece is transformed into an ultrafine-grained product having a desired strength.    
     
     
         13 . The product of  claim 12 , the process further comprising the step of annealing the corrugated workpiece of step (a).  
     
     
         14 . The product of  claim 12 , the process further comprising the step of annealing the straightened workpiece of step. (b).  
     
     
         15 . The product of  claim 12 , the process further comprising the step of lubricating the workpiece.  
     
     
         16 . The product of  claim 12 , the process further comprising the step of rotating the workpiece after performing step (a) and step (b) but before performing step (a) again.  
     
     
         17 . The product of  claim 12 , the process further comprising the step of warming the workpiece before and/or during step (a).  
     
     
         18 . The product of  claim 12 , the process further comprising the step of warming the workpiece before and/or during step (b).  
     
     
         19 . The product of  claim 12 , the process further comprising the step of cooling the workpiece before and/or during step (a).  
     
     
         20 . The product of  claim 12 , the process further comprising the step of cooling the workpiece prior to and/or during step (b).  
     
     
         21 . An apparatus for refining the grain size of a metal or alloy workpiece, comprising; 
 (a) means for corrugating the workpiece;    (b) means for straightening the corrugated workpiece; and    (c) means for delivering the workpiece from said corrugating means to said straightening means.    
     
     
         22 . The apparatus of  claim 21 , further including means for delivering the straightened workpiece to said corrugating means.  
     
     
         23 . The apparatus of  claim 21 , wherein said corrugating means comprises two rollers positioned such that a straight workpiece can enter between them, said rollers configured to impart deforming forces on the workpiece that result in corrugation of at least a section of the workpiece.  
     
     
         24 . The apparatus of  claim 21 , wherein said straightening means comprises two rollers positioned such that a corrugated workpiece can enter between them, said rollers configured to impart forces that straighten the corrugated section of the workpiece.  
     
     
         25 . The apparatus of  claim 21 , further including means for rotating the workpiece after it has been straightened by said straightening means and before it is corrugated again by said corrugating means.