Combination of sever plastic deformation and precipitation hardening processes affecting the mechanical properties in Al-Mg-Si alloy

Sever plastic deformation processing has been frequently used to refine grain size and to improve properties in metals and alloys. The impact of combination of equal channel angular pressing (ECAP) and precipitation hardening on mechanical properties of 6063 aluminum alloy was investigated in this paper. These two processes were also tested individually in order to know if the combination affects the microstructure and tensile properties. According the experimental results, the yield and ultimate strength increase twice and three times respectively after ECAP processing. Having the processed samples naturally aged, the microstructure and mechanical properties remain almost unchanged. However, artificial aging at 180 degrees C after ECAP, improves the ductility of the material and decreases the strength slightly due to dislocation annihilation occurring during heat treatment. It can be deduced that individual processes of ECAP and aging enhance some mechanical properties and worsen some others; but combination of these processes improves the material's properties. In order to compare quantitatively the overall mechanical properties a new factor, denoted by SNMP, is introduced which is the Sum of Normalized Mechanical Properties. According to the results, the value of SNMP for combination of processes is much higher than that for individual processes. (C) 2014 Elsevier Ltd. All rights reserved.