Microstructure and mechanical properties of Al–Mg alloy component produced by wire arc additive manufacturing

Among various additive manufacturing technologies, wire arc additive manufacturing (WAAM) is one of the most suitable methods for producing large-scale aluminum components, owing to its high deposition rate. However, achieving high-quality components by WAAM remains challenging, due to the heterogeneous microstructures and defects formed during WAAM process. To improve the performance of components, understanding the formation of the microstructure and defects is essential. In this study, the objective was to clarify the effect of heat input on grain morphology and the relationship between microstructure and mechanical properties of Al–Mg component manufactured by WAAM. Wall specimens were fabricated using Al–Mg wire (ER5356) with three different heat inputs, and their microstructures and mechanical properties were examined. The dominant grain morphology transitioned from feathery grains to columnar grains and finally to equiaxed grains. The number of porosity decreased with decreasing heat input. The component fabricated at the medium heat input exhibited superior tensile properties, i.e. ultimate tensile strength and elongation, by simultaneously suppressing the formation of detrimental feathery grains and porosity. These findings demonstrated that appropriate control of heat input can change the grain morphology and suppress the formation of porosity, thereby improving the tensile properties of Al–Mg components manufactured by WAAM.