Effects of manganese addition on tensile strength of AA6063 alloy for marine application

AA6063 alloy is a common materials used in boat and ship construction due to its lightweight and good strength. However, its strength is lower than steel's strength. For that reason, an improvement in strength is needed. In this work, an attempt has been made to improve the tensile strength of AA6063 alloy by adding manganese (Mn) element. From 0.5 to 2.5 wt.% of Mn was added to AA6063 alloy and melted together before being cast into a cylindrical steel mould. The alloy was solutionised at 535°C for 6 hours and followed by water-quenching. The alloy was then artificially aged at 200°C for 5 hours and followed by natural aging for 14 days. Tensile tests were carried out according to ASTM E8M-03 procedures. The combination of artificial and natural aging has increased the ultimate tensile strength of all AA6063 alloys (with and without Mn). The ultimate tensile strength of the alloys increased with the increase of Mn content. An addition of 2.5 wt% Mn has increased the ultimate tensile strength of AA6063 alloy to 189.55 MPa after solution treatment and artificial aging followed by 14 days natural aging compared to as-cast AA6063 alloy which has the ultimate tensile strength of 61.33 MPa.