Investigations on the Solid-State Additive Manufacturing of Al Alloy: Process, Microstructure, and Crystallographic Texture

Additive Manufacturing (AM) is crucial for Industry 4.0 where automation and real-time decision-making are to be performed with minimal human intervention. Most AM techniques involve melting metal powders layer-by-layer to build components which allows for complex geometries to be achieved; however, some challenges that inhibit it from becoming mainstream are hot cracking, porosity produced in the specimens, anisotropy and heterogeneity in the components with respect to the microstructure, mechanical properties, and crystallographic texture. Such problems could be overcome if AM is performed without melting. In this regard, additive friction stir deposition (AFSD) exhibits the highest potential for industrialization. AFSD involves depositing a solid metal feedstock bar layer-by-layer while being heated by a rotating tool. In this work, the process, microstructure, crystallographic texture, and hardness of Al 6082 alloy after AFSD have been investigated. A fine-grained microstructure was obtained. However, there was a reduction in the hardness by 54%. This could be due to the precipitate coarsening and dissolution during the processing.