Resumo:
The high-strength aluminium alloy AA-7075-T6 is widely used in the aerospace, military, and automotive sectors owing to its excellent strength-to-weight ratio. However, fusion welding of this alloy presents major challenges, particularly its high susceptibility to hot cracking, secondary phase precipitation, and porosity formation. This study investigates the influence of mechanical vibration applied during the welding of AA-7075-T6 using the Gas Metal Arc Welding (GMAW) process with the Surface Tension Transfer (STT®) mode. Different welding parameters and vibration frequencies were assessed, with emphasis on porosity, microstructure, and hardness of the welded joints. The results demonstrated that vibration during welding promoted significant metallurgical and mechanical improvements, including modification of the morphology and reduction in the size of secondary phases in the fusion zone, a marked decrease in coarse particles in the heat-affected zone (HAZ), reduced loss of microhardness in the welded regions, microstructural refinement at the interface with the base material, and a narrowing of the HAZ. Moreover, a substantial reduction in porosity was observed, with the most effective performance achieved at a frequency of 183 Hz.It is concluded that the controlled application of mechanical vibration during the welding of AA-7075-T6 is a viable and promising technique, capable of improving the metallurgical quality and mechanical performance of welded joints, thereby broadening the potential applications of this alloy in critical aerospace, aeronautical, and automotive components.
