Modeling the Strain Rate and Stress State Effects of Solid State AFS Additive Manufactured Aluminum Alloys

In this research, a microstructure-based internal state variable (ISV) plasticity-damage model was used to model the mechanical behavior of Additive Friction Stir (AFS) processed 2219 aluminum alloy. The solid state additive manufacturing process referred to as AFS provides a new path for repair, coating, joining and additive manufacturing of metals and metal matrix composites. Electron Backscattered Diffraction (EBSD) was used to characterize the as-fabricated microstructure, where a fully-dense equiaxed grain morphology with finer grains formed by dynamic recrystallization (DRX) was observed. Micro-hardness mapping of the as-built structures and monotonic tension and compression experiments at both quasi-static (0.001/s) and dynamic (2500/s) strain rates were performed to obtain the set of plasticity and damage constants necessary to capture the strain rate and stress state behavior of this additive material. The high rate experiments exhibited increased flow stress when compared to the quasi-static experiments, as expected.