Microstructure Prediction from Smooth Particle Hydrodynamics Process Simulations of Additive Friction Stir Deposition

Additive friction stir deposition (AFSD) is a solid-state additive manufacturing method that exploits frictional heat generation and severe plastic deformation to achieve metallurgical bonding during layer-by-layer deposition. AFSD can be used for additive manufacturing of bulk components or repair of aluminum alloys as the sub-solidus processing temperatures can be beneficial over fusion-based alternatives. Due to dynamic recrystallization during AFSD processing, significant evolution of the microstructure can occur which can lead to substantial gradients in grain and intermetallic particle size. In this study, we present a history dependent modeling framework to predict the microstructure evolution in the AFSD process through mesh-free numerical simulations. In this work, experimentally quantified relationships between grain and intermetallic particle size as well as temperatures and strain rates were incorporated into a smooth particle hydrodynamic simulation framework to predict the microstructure after AFSD processing. The SPH simulation approach showed reasonable agreement between the model predictions and experimental results of grain and intermetallic particle size distribution after AFSD processing.