Torsional severe plastic deformation method for metal bar, employing surface polishing to improve mechanical properties of metal bar

Abstract

The present invention relates to a torsional severe plastic deformation method for a metal bar to which surface polishing is applied to the metal bar to improve the mechanical properties of the metal bar. According to an embodiment of the present invention, there is provided a torsional severe plastic deformation method for a metal bar, which includes: applying torsion to a metal bar; and removing a surface defect on the surface of the metal bar, the surface defect being caused by the applying of torsion, wherein the removing of the surface defect is carried out in a continuous manner in which the removing of the surface defect is performed together with the applying of torsion or in a discontinuous manner in which the applying of torsion is temporarily stopped and then the applying of torsion is performed, and the removing of a surface defect increases the amount of torsional rotation or the shear strain applied to the metal bar.

1 . A torsional severe plastic deformation method for a metal bar, comprising:
 applying torsion to a metal bar; and   removing a surface defect on the surface of the metal bar, the surface defect being caused by the applying of torsion, wherein   the removing of the surface defect is carried out in a continuous manner in which the removing of the surface defect is performed together with the applying of torsion or in a discontinuous manner in which the applying of torsion is temporarily stopped and then the applying of torsion is performed, and the removing of a surface defect increases the amount of torsional rotation or the shear strain applied to the metal bar.   
     
     
         2 . The torsional severe plastic deformation method for a metal bar of  claim 1 , wherein the removing of a surface defect comprises a polishing process. 
     
     
         3 . The torsional severe plastic deformation method for a metal bar of  claim 2 , wherein a silicon carbide (SiC) grinding paper is used for the polishing process. 
     
     
         4 . The torsional severe plastic deformation method for metal bars of  claim 2 , wherein the polishing process is performed by using a polishing material that can reduce the surface roughness of the metal bar according to the increase in the amount of torsional rotation or shear strain. 
     
     
         5 . The torsional severe plastic deformation method for a metal bar of  claim 4 , wherein when the polishing process is performed in a discontinuous manner, the polishing process is performed so that the surface roughness of the metal rod is 5 um or less per torsion process.