Influence of aging parameters on the mechanical properties of 6063 aluminium alloy

The 6063 aluminium alloy were given various heat treatments at under-aged, peak-aged and over-aged temperatures. The effect of precipitation on the tensile strength, yield strength, hardness, ductility and number of cycles required to fail the alloy at constant stress was investigated. The variation in time and temperature have improved the mechanical properties of the Al-alloy, whereas the ductility has decreased. The experimental work has revealed that time and temperature play a very important role in the precipitation hardening process of the Al-alloy. The initial increase in the tensile strength, yield strength, hardness and fatigue is due to vacancies assisted diffusion mechanism and formation of high volume fraction of guinier preston (GP) zones, which disturbs the regularity in the lattices. In over-aging of the alloy, the size of the individual particle increases, but the number of particles decreases. This causes few obstacles to the movement of dislocations, therefore, the mechanical properties decreases. The scanning electron microscope (SEM) study of the under-aged alloy have exhibited facet fatigue fracture surface, whereas the peak-aged and over-aged alloy show a mixed mode of fracture, i.e. facet fracture with striation and also intergranular fracture.