Modelling of Alloying Elements and Ageing Effects on Mechanical Properties of 6063 Aluminium Alloys

Abstract

Abstract: This study seeks to optimise the mechanical properties of the aluminium alloy 6063, taking into account the levels of alloying elements and artificial ageing heat treatment conditions. The aluminium alloys, particularly those belonging to the 6000 series, are known for their good mechanical properties, which include ductility, weldability, resistance to corrosion, and strength-to-weight ratio, the combination of preferred properties makes them suitable for wide diverse industrial applications. The study explores how the mechanical properties of 6063 aluminium alloys, measured as hardness (H), elongation percentage (%El), yield and ultimate tensile strengths (YTS) and (UTS), are dependent on the change in weight percentages of the following alloying elements Silicon (Si), Iron (Fe), Manganese (Mn), and Magnesium (Mg), as well as the difference in ageing temperature and time affects these mechanical properties. This study utilised a hybrid experimental methodology with computational modelling tools using the application of Design of Experiment (DoE) and Response Surface Methodology (RSM) to investigate correlations between these alloying and ageing variables, together with the mechanical properties of the aluminium alloy. Numerical models were constructed to evaluate the mechanical properties as a function of the levels of these variables. The alloying and ageing conditions were optimised to meet the mechanical properties requirements using a combination of optimisation techniques, the desirability method and genetic algorithm (GA). The optimum conditions to maximise the mechanical properties of the 6063 alloy for Si, Fe, Mn, and Mg were found to be (0.559, 0.100, 0.012, 0.453) respectively. The optimum ageing temperature and time were found to be 175°C and 5.812 Hrs. The study findings illustrate how the different mechanical properties, such as hardness, ductility, UTS, and YTS, are affected by the variations and interactions of the alloying elements levels and the ageing conditions. The study's conclusion and recommendations for future research work suggest an opportunity for more comprehensive studies on the influence of the change in alloy composition. It also suggests a wider investigation of the heat treatment processes the alloy undergoes before and after artificial ageing. Broader investigations have been suggested to provide a more compressive understanding of the factors that can be optimised to meet the requirements for different mechanical properties.