Gas Metal Arc Welding (GMAW) is a versatile and efficient technique used across industries. This thesis investigates the behaviour of aluminium alloys in GMAW. Specifically alloys containing magnesium, focusing on droplet temperature, evaporation rates and a novel energy balance. This work presents comprehensive experimental procedures and detailed analysis, providing valuable insights into the GMAWprocess. This work presents a novel approach using a solid-state calorimeter system to obtain reliable temperature measurements. Key findings reveal that Mg-containing alloys exhibit lower droplet temperature and generate higher deposition rates, across different wire diameters. The research highlights that droplet temperature decreases with Mg-content, but not substantially with wire diameter. The evaporation model developed in this work identifies the mass resistance in the gas boundary layer as the dominant mechanism for evaporation. Additionally, the energy distribution analysis emphasizes the need to lower droplet temperatures while maintaining a stable arc to improve deposition rates. Lastly it provides the groundwork for future research in controlled metal transfer of Al-Mg alloys.