Heat-input-oriented optimization and microstructural characterization of AC TIG welded thick AA5083 aluminum alloy

Abstract The current study focuses on optimizing AC TIG welding parameters to achieve higher hardness and better control of the heat-affected zone (HAZ) using a Taguchi L16 orthogonal array on 10 mm-thick AA5083 alloy. The study establishes a heat-input-oriented optimization framework for AC TIG welding of thick AA5083 aluminum alloy by integrating statistical optimization with metallurgical characterization. The control parameters, including AC pulse modulation frequency, peak current, and welding speed, were selected to achieve improved hardness and a smaller heat-affected zone (HAZ). Qualitative microstructural characterization using optical microscopy, SEM, and XRD indicated comparatively finer weld morphology and fewer visible defects under lower heat-input conditions, while XRD confirmed the presence of the α-Al matrix together with Al₁₃Fe₄, Mg₂Si, and minor Si phases. The results indicate that lower heat input contributes to improved hardness retention and reduced HAZ width within the investigated parameter range, providing practical guidance for AC TIG welding of thick AA5083 aluminum alloy.