Investigation on the Aging Responses and Fracture Surface Morphology of Al- Mg –Si Alloys with Different Weight Percent of Mg and Si Compositions
Che Nor Aiza Jaafar, Ismail Zainol and Mohamad Qaizzullah
The mechanical properties of Al-Mg-Si alloys are depending upon many factors such as alloy composition, casting method, heat treatment procedures (solution treatment temperature, aging time and temperature) and other parameters which could affects the aging response and behaviors. In this study, aging response and fracture surface morphology of two Al-Mg-Si alloys with different wt% of Mg and Si compositions of Al-Mg-Si alloys were investigated. The experimental procedures were started with a heat treatment process where firstly both alloy samples were solution treated at 540 °C for 30 minutes, followed by quenched into cold water. The solution treated alloy samples were artificially aged at an elevated temperature of 170 oC for 0.1 to 100 hours. The aging response and mechanical properties were examined by Vickers hardness and tensile test. The surface fractured morphology from the tensile specimen in peak-aged condition at 170 °C was carried out using a field emission scanning electron microscope (FESEM). It was found that the composition of Mg and Si present in the alloys affects the aging response and mechanical properties. As the composition of Mg and Si increased, the mechanical properties of the alloys also increased and gave a stronger aging response to the alloys. The FESEM analysis exhibited that the alloy P which contained higher composition of Mg and Si showed a less ductile behaviour and lower elongation properties, hence the results of the FESEM analysis are in line with the results of hardness and tensile test.