Effect of ECAP process on mechanical properties and microstructure of AA-6061 recycled chips

Abstract

The oxidation of aluminum machined chips makes successful recycling via the traditional re-melting technique difficult. A viable solution to this problem is to utilize solid-state recycling to transform aluminum machined chips directly into semi-finished goods, eliminating the costs of the re-melting process and minimizing CO2 emissions. In the present study, Al-6061 alloy chips have been recycled using hot extrusion followed by severe plastic deformation at ambient temperature to examine the material's mechanical properties and microstructures. The current study investigates the effects of equal channel angular pressing samples after (1, 2, and 4) cycles using a die with 90° and 20° angles, a strain of 1 was applied each pass for a maximum of four cycles at room temperature, through different routes (BC, C) on the mechanical properties of recycled specimens before and after the process. Observations showed a significant improvement in the characteristics of recycled chips exposed to hot extrusion followed by the ECAP technique. Maximum ultimate tensile strength (265, and 238 MPa) maximum yield strength (149, and 136 MPa), and elongation to failure (46 and 41%) for both routes were obtained. Moreover, each pass increases yield strength ultimate tensile strength, and micro-hardness while increasing elongation to failure. The mechanical characteristics of ECAPed specimens were higher than the extruded specimen. The mechanical properties and microstructures of solid-state recycled Al-6061 alloy chip samples were significantly influenced by the number of passes and route types.