Influence of aging treatment on mechanical properties and microstructure of Al6061-nano Al2O3 Composites

Aluminum and its alloys have an ever growing demand in many industries such as aerospace, automotive due to their high strength to weight ratio and corrosion resistance. Aluminum−magnesium−silicon (Al−Mg−Si) denoted as 6xxx series alloys are medium strength heat treatable alloys and have good formability. Work hardening and precipitation hardening are common strengthening mechanisms of 6xxx series of aluminum alloys. The influence of combination of different designated precipitation hardening on the hardness and tensile properties of 6061 aluminum alloy was investigated. In this study, the mechanical properties and microstructure of a commercially available AA6061 alloy aged to various levels were studied. Peak-aged conditions were reached in this particular alloy after a 30 min heat treatment at 220°C. The variation of the yield stress, ultimate tensile strength, ductility with aging time is measured and discussed in relation to the microstructural changes induced by the heat treatment. In order to investigate the microstructure, specimens were electro-polished and etched by Weck reagent. The results indicate that applying single aging at 220°C for 30 min improves the elongation. T6 Al6061-nanoAl2O3 matrix rolled has lower UTS of 315 MPa in comparison to a higher value of 390 MPa for the non-heat treated sample. It seems that hardening induced by T6 precipitates was less than the work hardening attributed to the matrix hardening during sheet rolling.

Keywords:

Al-Al2O3 Nano composite , Precipitation hardening , Mechanical properties , Electro-polishing , Microstructure