Abstract
M.Ing. (Mechanical Engineering)
Metal matrix composites have been used in recent times to achieve better mechanical properties of materials and improved general performance of welded structures. Metal Inert Gas (MIG) welding also known as Gas Metal Arc welding (GMAW) is an arc-welding process, which joins metals by heating them with an arc between a continuously fed solid electrode and the work piece. Aluminium and its alloys provides unique properties which makes it one of the most attractive metallic, economical, versatile material for a broad range of uses in engineering applications, such as aerospace, automobile and mineral processing industries. Against this background, aluminium is not suitable for all engineering applications, and it sometimes requires some degree of reinforcement, particularly in a corrosive environment and/or at elevated temperatures.
This study focuses on ascertaining the integrity of MIG welded pure aluminium reinforced with copper powder at the weld zone. Material characterizations of the aluminium (Al) and copper (Cu) metal matrix composites produced via the MIG welding process were conducted. The pure aluminium, AA1100 sheets were machined to a 45o v-grooved shape, and then filled with copper powder particles and welded. The welded samples were characterised by performing mechanical tests (tensile testing using the Zwick Roell 2250 tensile machine and microhardness profiling using a digital Vickers microhardness testing machine) and microstructural investigation via the scanning electron microscope (SEM), the energy-dispersive spectroscopy (EDS) and optical microscope. This was followed by X-ray diffraction analysis (XRD), and corrosion test by electrochemical polarization method. The results revealed that the addition of copper powder significantly increased the hardness property of the welds, as the welds with copper powder particles reinforcement showed higher hardness values when compared to those without the copper powder particle reinforcement. The highest tensile strength was obtained from the copper reinforced sample. Furthermore, the microstructures revealed finer grain structures for the reinforced samples. The samples with reinforcement also exhibited better corrosion properties.
It was therefore, concluded that the aluminium (Al) and copper (Cu) metal matrix composite welded via MIG welding produced better mechanical properties, as well as increased corrosion resistance behaviour, and it can definitely be recommended for typical aerospace applications