Surface modification method for light metal casting

Abstract

There is provided a surface modification method for a light metal casting that enables, with Friction Stir Processing, to further refine a surface at a portion at which the strength is especially required. A surface modification method for a light metal casting with Friction Stir Processing in which a rotating shaft and a rotator are rotated and fed while the rotating shaft and the rotator are being pressed against a surface of a casting to modify the surface of the casting, the method includes feeding the rotating shaft and the rotator while rotating the rotating shaft and the rotator in a manner such that a side at which a rotating direction of the rotating shaft and the rotator coincides with a feeding direction is positioned at a portion at which increase in the strength is desired with modification of the light metal casting.

What is claimed is: 
     
         1 . A surface modification method for a light metal casting with Friction Stir Processing in which a rotating shaft and a rotator are rotated and fed while the rotating shaft and the rotator are being pressed against a surface of a casting to modify the surface of the casting, the method comprising feeding the rotating shaft and the rotator while rotating the rotating shaft and the rotator in a manner such that a side at which a rotating direction of the rotating shaft and the rotator coincides with a feeding direction is positioned at a portion at which increase in the strength is desired with modification of the light metal casting. 
     
     
         2 . The surface modification method for the light metal casting according to  claim 1 , further comprising:
 performing the feeding in the same feeding direction a plurality of times; and   performing each feeding by shifting, in parallel, a next feeding path from a previous feeding path by a predetermined width equal to or less than a diameter of the rotator.   
     
     
         3 . The surface modification method for the light metal casting according to  claim 1 , further comprising feeding the rotating shaft and the rotator according to a path circling along an edge of the light metal casting in a manner such that the side at which the rotating direction of the rotating shaft and the rotator coincides with the feeding direction is positioned at the edge of the light metal casting.