Analysis of the Structure and Temperature Distribution in a Duralumin Alloy Weld during Friction Stir Welding

Using complex theoretical and experimental methods of analysis, the influence of diffusion and deformation processes on the chemical composition and structure of a welded joint of plates made of D16T aluminum alloy under friction stir welding conditions was assessed. To reproduce the temperature conditions in the welding zone and assess the possible causes of changes in the structure and phase composition of the material in the weld region, methods of mathematical modeling of thermal processes were used. The resulting theoretical calculations were tested and confirmed using experimental methods of structural analysis (X-ray structural analysis and scanning electron microscopy) and microhardness measurements. A change in the content of silicon, copper, and aluminum in the composition of the solid solution of the material under study was detected, as well as a change in the phase composition (a decrease in the amount of the Al₁₂Fe₃Si phase and the appearance of the AlCuFeMnSi phase), which is associated with mass transfer in the zone of the welded joint under friction stir welding conditions.