Abstract

This paper presents the effectiveness of optimising single-thermal ageing characteristics of A356 aluminium alloy using
Taguchi methodology. In this research work, Taguchi’s L9 (3^4) orthogonal array was successfully used forexperimental
design to study the influence of artificial ageing treatment (T6) parameters on the tensile properties of A356 aluminium alloy.
Ageing parameters such as solutionizing temperature, solutionizing time, ageing temperature and ageing time were employed
in this study. The tensile test and microstructural analysis were conducted using a universal testing machine and optical
metallurgical microscope respectively. Also, the experimental data were analysed with the aid of Minitab 18 statistical
software based on the larger the better criterion. The results showed that the optimum value obtained for tensile strength
based on Taguchi prediction was 136.23 N/mm2 and 11.23% for percent elongation. Thus, the level of the improvement
attained for both tensile strength and percent elongation at the optimized condition was 50 % higher than that of the as-cast
sample properties. The results further revealed that ageing temperature and solutionizing time were the prominent factors
influencing the tensile properties of T6-treated A356 alloy. The microstructural analysis confirmed that the improvement of
the tensile properties of T6-treated A356 aluminium alloy could be directly related to the spheroidization of eutectic Silicon
(Al-Si) and the presence of Mg2Si inter-metallicprecipitates in the structure.

Key words: Aluminium Alloy; Artificial Ageing; Optimization; Taguchi method; Tensile Properties