Mechanical and corrosion properties of 6061 aluminum alloys recycled by hot-extrusion of cutting chips

Abstract

From cutting chips of 6061 aluminum alloy, recycled materials' plates were fabricated by extrusion and rolling. Three kinds of cutting chips, which were dry-cutting chips without cutting oil, wet-cutting chips with cutting oil and clean chips obtained by washing of the wet-cutting chips, were used for the recycling process. Moreover, non-recycled materials' plates which processed by the same extrusion and rolling using virgin materials of the same alloy as the case of the recycled materials were prepared for comparison. These four kinds of plates were characterized by carrying out ultimate analysis by fluorescent X-ray spectrometer and infrared absorption spectrometer, optical microscopic and SEM observation, tensile test, and corrosion test. Consequently, a significant difference in structures, tensile properties, and corrosion resistance was not recognized among three kinds of recycled materials, it became clear that cutting oil and detergent hardly influence the characteristics. Moreover, it was found that recycled materials had smaller crystal grain than that of non-recycled materials, and excelled in both strength and corrosion resistance. The conclusion that recycling of the cutting chips by extrusion and rolling was very promising in 6061 aluminum alloys was obtained.

Solid-state recycling of aluminium alloy swarf through cold profile extrusion and cold rolling

“…It would be financially impractical to completely remove the extraneous matter remaining on the swarf (e.g., cutting oil), and it has been reported that in the recycling of 6061 aluminium alloy machining swarf through hot extrusion, the effects of the cutting oil on the mechanical properties of the extrudant are negligible (Suzuki et al, 2003). In the present study, however, the machining swarf was carefully cleaned to exclude any factors other than the properties of the target material.…”

“…In recent years, related studies using backward extrusion (Murakoshi et al, 2007), forward extrusion followed by normal rolling (Suzuki et al, 2003) or differential speed rolling (Suzuki et al, 2007), as well as special processing methods that can introduce large strain such as equal-channel angular pressing (ECAP) , high pressure torsion (HPT) (Takahashi et al, 2009), cyclic extrusion compression (CEC) (Peng et al, 2009) and friction extrusion (Tang and Reynolds, 2010) have been reported. Although the studies mentioned above have targeted single-phase materials, the solid-state recycling of machined chips into composite materials has also been attempted.…”

Solid-State Recycling of Aluminum Alloy (AA-6061) Chips via Hot Extrusion Followed by Equal Channel Angular Pressing (ECAP)

“…While, in case of cold compaction the extrusion ratio must higher than 25 in order to obtain sound bonding. Suzuki et al [10] compacted the AA-6061 chips and followed by hot extrusion at various extrusion ratios and temperatures. Nakanishi et al [11] examined the relationship between the extrusion ratio and mechanical properties of hot extruded machining chips of AZ91 magnesium alloy.…”