Microstructure characteristics under varying solidification parameters in different zones during CMT arc additive manufacturing process of 2319 aluminum alloy

The microstructure affects the performance of the formed component during the wire arc additive manufacturing (WAAM) process of aluminum alloy. The present research utilized a finite element model to investigate the temperature field, thermal cycle curve, temperature gradient and cooling rate curve of the deposition layer at different positions in the WAAM process. The microstructure distribution and grain size variation of the deposition layer at different positions were examined according to the experimental results. The microstructure evolution of the deposition layer in the WAAM was simulated using a macro-micro coupled grain growth model. The variation law of solid phase and liquid phase distribution with solidification time steps of molten pool under varying temperature gradients is analyzed. The results indicated that the average length and width of the grains continuously decrease from right to left in the top zone of the deposition layer. When the temperature gradient increases to a certain extent, both the liquid phase area difference and the solid phase area ratio difference within the same time step gradually decrease with the development of the temperature gradient. This research supplies a reference for optimizing the microstructure of WAAM aluminum alloy by adjusting the heat input and solidification parameters.