Influences of chip characteristics and extrusion conditions on the properties of a 6061 aluminum alloy recycled from cutting chips

Abstract

Possibilities of the consolidation process using hot extrusion were investigated in order to recycle the cutting chips of the aluminum alloy efficiently. Influences of the size and the cleanliness of the cutting chips and extruding conditions on mechanical properties and corrosion resistance of the recycled materials were examined to optimize the processing condition. Cutting chips were collected from 6061 aluminum alloy round bars using the lathe, and they were pretreated to prepare chips with different cleanliness. The cutting chips were forced into a pure aluminum can, and extruded under various extrusion ratios and temperatures. The obtained extrusions with T6 heat-treatment were defined as "Recycled materials". Optical microscopic observation, EBSP analysis, tensile tests and immersion corrosion tests were carried out to the recycled materials. Mechanical properties and the corrosion resistance of the recycled materials were almost equivalent to the highest values of the virgin material. Higher extruding temperature was required in order to consolidate finer cutting chips. However, the recycled materials using fine chips showed improved strength parallel to the extrusion direction.