Optimization of Mechanical Properties of Age-Hardened 6063 Aluminium Alloy Via Diffusion Annealing

This paper investigates the influence of diffusion annealing on some mechanical properties of 6063 aluminium alloy. Standard tensile and hardness test samples were subjected to diffusion annealing at 570ºC for 2, 2.5, 3 and 3.5 hours respectively prior to T6 tempering, another set of these samples were directly T6 tempered without prior diffusion annealing treatment. The two sets of samples were subjected to tensile and hardness tests and the evolving microstructure were characterized using Scanning Electron Microscope (SEM). Results indicated an increase in the mechanical properties for samples subjected to diffusion annealing prior to aging as compared to conventionally aged samples and there was also a remarkably good combination of mechanical properties especially percentage elongation (ductility) and yield strength. Samples treated by this technique find useful applications in the development of sustainable infrastructure in marine environments where other materials like 7075 aluminium or steel perform poorly as a result of ingress of chloride ion.