Recycling of 6061 Aluminum Alloy Cutting Chips Using Hot Extrusion and Hot Rolling

Abstract

Possibilities of the consolidation process using hot extrusion and subsequent hot rolling were investigated in order to recycle the cutting chips of the aluminum alloy efficiently. For the rolling process, differential speed rolling (DSR) was also applied in addition to normal rolling. Several kinds of cutting chips with different size and cleanliness were collected through turning 6061 aluminum alloy round bars. From these cutting chips, recycled material sheets were produced under various processing conditions via hot extrusion and subsequent hot rolling. Non-recycled material sheets were also prepared for comparison. All samples were characterized by optical microscopy, SEM(EBSP), X-ray texture analysis, tensile test and corrosion test. As a result, it was found that the recycled material sheets produced under optimum processing conditions had smaller grain sizes than those of the non-recycled ones, therefore the mechanical properties and the corrosion resistance of the recycled material sheets were almost comparable to those of the non-recycled ones. Moreover, concerning the DSR processed sheets, the traces of the chip interface, which were clearly observed in the normally rolled ones, almost disappeared, and the appearances were remarkably improved. Then the DSR processed sheets significantly surpassed the non-recycled ones in the tensile properties and the corrosion resistance.