Method and device for generating deformation twinning in a metal

Abstract

A method of generating twin lamellas in a metal body includes the steps of introducing the metal body into a chamber, filling the chamber with a cooling medium having a temperature that will enable generation of twin lamellas in the metal body upon deformation thereof, and deforming the metal body while the latter is surrounded by the cooling medium. The cooling medium surrounds the metal body upon deformation of the latter is in a gaseous state. The present disclosure also relates to a device for generating twin lamellas in the metal body, the device including a chamber, a chamber inlet connected to a cooling medium source, and a deformation device arranged to deform the metal body. The deformation device is positioned inside the chamber so that the metal body will be surrounded by the cooling medium in a gaseous state while being deformed by the deformation device.

1 . A method of generating twin lamellas in a metal body, comprising the steps of:
 introducing said metal body into a chamber;   filling said chamber with a cooling medium having a temperature arranged to enable generation of twin lamellas in the metal body upon deformation thereof; and   deforming said metal body while the metal body is surrounded by said cooling medium, wherein the cooling medium surrounding said metal body upon deformation of the metal body is in a gaseous state.   
     
     
         2 . The method according to  claim 1 , wherein the temperature inside the chamber is controlled by controlled introduction of said cooling medium into the chamber in at least two different locations within the chamber, wherein the cooling medium in a first location is directed directly onto the metal body being deformed, and in a second location is directed onto a deformation device used to deform said metal body. 
     
     
         3 . The method according to  claim 1 , wherein the cooling medium has a temperature in the range of about −80° C. to about −195° C. 
     
     
         4 . The method according to  claim 1 , wherein said cooling medium consists essentially of nitrogen. 
     
     
         5 . The method according to  claim 1 , wherein said cooling medium is introduced in a liquid state into the chamber and is permitted to change to a gaseous state once introduced into said chamber. 
     
     
         6 . The method according to  claim 1 , wherein said metal body is an elongated body which is continuously introduced into said chamber through an opening in the chamber, and wherein the cooling medium in a gaseous state is taken from the chamber and used for pre-cooling of parts of said metal body that have yet not been introduced into the chamber. 
     
     
         7 . The method according to  claim 1 , wherein said metal body is a wire or tube and wherein said deformation of said metal body inside said chamber includes a reduction of a thickness of the-wire or tube. 
     
     
         8 . A device for generating twin lamellas in a metal body, said device comprising:
 a chamber;   a chamber inlet connected to a cooling medium source; and   a deformation device for deforming said metal body, said deformation device being positioned inside said chamber, wherein the deformation device is positioned so that the metal body will be surrounded by said cooling medium in a gaseous state while being deformed by said deformation device.   
     
     
         9 . The device according to  claim 8 , further comprising temperature control means for controlling the temperature inside said chamber by controlling the introduction of cooling medium into the chamber. 
     
     
         10 . The device according to  claim 9 , wherein said temperature control means includes at least a first and a second independently controllable nozzle positioned inside the chamber and each nozzle being configured to introduce cooling medium into the chamber, wherein the first nozzle is configured to direct cooling medium directly onto the metal body during deformation, and wherein the second nozzle is configured to direct cooling medium onto the deformation device during deformation. 
     
     
         11 . The device according to  claim 10 , wherein said metal body is an elongated body, and further comprising means for continuous introduction of said metal body into the chamber. 
     
     
         12 . The device according to  claim 11 , wherein the means for continuous introduction of said metal body into the chamber is at least one drawing block positioned inside the chamber, wherein the first nozzle is configured to direct cooling medium directly onto the metal body being wound onto the drawing block, and wherein the second nozzle is configured to direct cooling medium onto an inner wall of the drawing block. 
     
     
         13 . The device according to  claim 11 , further comprising a channel through which said elongated metal body is continuously introduced into the chamber, said chamber having an outlet through which cooling medium in a gaseous state is permitted to leave the chamber and be introduced into said channel for pre-cooling said metal body before the body is introduced into the chamber. 
     
     
         14 . The device according to  claim 8 , wherein said chamber is a generally closed chamber, and wherein the device further comprises means for controlled evacuation of cooling medium in a gaseous state from said chamber. 
     
     
         15 . The device according to  claim 8 , wherein said cooling medium source is a liquid nitrogen source. 
     
     
         16 . The device according to  claim 8 , wherein said metal body is a wire or tube and said deformation device includes at least one die for reduction of a diameter of the wire or tube.