Heat input represents a critical process parameter that significantly influences the quality of tungsten inert gas (TIG) welding. In this study, a comprehensive investigation of heat input effects on the welding quality of thin-gauge aluminum alloy was conducted through integrated theoretical analysis and experimental validation. The research established an optimal heat input range of 296–321 J/mm for 3 mm thick 5083 aluminum alloy plates in TIG welding applications, within which welded joints demonstrated minimal defect formation and superior mechanical performance. Both numerical simulations and experimental results revealed a distinct non-monotonic relationship between heat input and joint properties: when operating below the optimal range, progressive increases in heat input resulted in corresponding improvements in fusion characteristics and mechanical properties. Conversely, exceeding the optimal range led to progressive grain coarsening within the weld microstructure, accompanied by measurable degradation in key mechanical properties including tensile strength and hardness.

The wetting behaviors of Al-Si-Cu-Mg-Zn brazing materials on 5083 aluminum alloy substrate were investigated through changing the proportion of Mg from 0 to 2 wt.%. The experimental results showed that the welding process goes through the three following stages: slow spreading, fast spreading, and stabilizing. The wettability of the brazing material was improved effectively, and the porosity of the interfacial layer was reduced, with the addition of Mg. With Mg content at 1 wt.%, the wetting diameter reached a maximum value of 20.46 mm. The reaction mechanism of the wetted interfacial layer between the brazing material and substrate alloy was illustrated with dynamic data, provided through experimentation and simulated thermodynamic calculation, and showed that the wetting behavior of the resultant Al-7.5Si-15Cu-1Mg-5Zn brazing material was dominated primarily by a diffusion reaction from elemental magnesium.

This study investigates the effect of TIG weld pool temperature on the microstructure and mechanical properties of crack-repaired joints in 7072 aluminum alloy. To address poor temperature stability and slow response in indirect temperature control during TIG welding by adjusting the parameters, a new closed-loop molten pool temperature control method is proposed. Experimental comparisons were conducted to evaluate its effectiveness. The results show that using real-time molten pool temperature as direct feedback allows the welding current to be adjusted dynamically. This approach enables precise control of heat input. It also achieves real-time tracking and stable regulation of the molten pool temperature during welding. Temperature-controlled welding yields a more uniform joint microstructure with reduced porosity. Notably, the joint exhibits optimal comprehensive mechanical properties at 1825 °C, with a tensile strength of 328 MPa and an elongation of 9.9%. Overall, precise control of the TIG weld pool temperature effectively improves the quality and performance uniformity of aluminum alloy crack repairs.

This study investigated the microstructural evolution of Al-7.5Si-15Cu-5Zn brazing alloys modified by adding 0.5 wt.% Mg and xCe (x = 0.05, 0.1, 0.2, 0.3, 0.4 wt.%) . The mechanical properties of the corresponding brazing joints on 5083 aluminum alloy were measured with the aid of first-principle calculations. Results show that Mg and Ce elements refine the microstructure of Al-7.5Si-15Cu-5Zn brazing alloys by changing the morphology of the intermetallic phases. There is an interface zone between the brazing alloy and the base alloy in the joints and the thickness of interface zone evolves with the Mg addition and Ce contents. The virtual crystal approximation (VCA) method predicts the best mechanical properties of the joints using Al-7.5Si-15Cu-5Zn-0.5 Mg-0.2Ce brazing alloy, exhibiting the measured tensile strength, elongation and microhardness of 261.14 MPa, 11.95% and 194.6 HV_0.2, respectively. Compared to the base brazing alloy without Mg and Ce additions, the tensile strength is increased by 42% and the elongation is improved by 47%.

This study investigated the microstructural evolution of Al-7.5Si-15Cu-5Zn brazing alloys modified by adding 0.5 wt.% Mg and xCe (x = 0.05 wt.%, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%). The mechanical properties of the corresponding brazing joints on 5083 aluminum alloy were measured with the aid of first-principle calculations. Results show that Mg and Ce elements refine the microstructure of Al-7.5Si-15Cu-5Zn brazing alloys by changing the morphology of the intermetallic phases. There is an interface zone between the brazing alloy and the base alloy in the joints and the thickness of interface zone evolves with the Mg addition and Ce contents. The virtual crystal approximation (VCA) method predicts the best mechanical properties of the joints using Al-7.5Si-15Cu-5Zn-0.5Mg-0.2Ce brazing alloy, exhibiting the measured tensile strength, elongation and microhardness of 261.14 MPa, 11.95% and 194.6 HV _0.2 , respectively.