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Owing to the occurrence of hot cracking during solidification and vaporization of solute elements during melting, beam-based additive manufacturing has encountered serious problems in printing high-strength, nonweldable Al alloys. After aging, the mechanical properties of these alloys are often substantially inferior to their wrought alloy counterparts. Here, a deformation-based additive process is used for printing high-strength 7075 Al alloy (i.e., AA7075), wherein frictional heating is leveraged to enable rapid plastic deformation. The as-printed material consists of a refined, equiaxed microstructure and shows no surface or interface porosity. After proper solution treatment and aging, the yield strength, ultimate tensile strength, and elongation of the printed AA7075 are measured as 477 MPa, 541 MPa, and 8.2%, respectively. These values are a notable improvement from those published for beam-based additive manufacturing and are comparable to the typical properties of wrought alloy AA7075. With a comparison to the feed material, these values account for 95% of the yield strength, 94% of the ultimate tensile strength, and 78% of the elongation of the wrought AA7075-T6 with the exact same composition. Additional printing and testing show that wrought-like mechanical properties can be consistently achieved using this approach without adding new elements or nanoparticles. Unlabelled Image • Non-weldable 7075 Al is additively manufactured by deformation-based additive manufacturing without hot cracking or porosity. • Wrought-like mechanical properties, including strength and ductility, are achieved in the printed 7075 Al. • Fine, equiaxed microstructures are achieved in the as-printed state without the addition of new elements or nanoparticles. [ABSTRACT FROM AUTHOR]

Wire-based metal additive manufacturing utilizes the ability of additive manufacturing to fabricate complex geometries with high deposition rates (above 7 kg/h), thus finding applications in the fabrication of large-scale components, such as stamping dies. Traditionally, the workhorse materials for stamping dies have been martensitic steels. However, the complex thermal gyrations induced during additive manufacturing can cause the evolution of an inhomogeneous microstructure, which leads to a significant scatter in the mechanical properties, especially the toughness. Therefore, to understand these phenomena, arc-based additive AISI 410 samples were fabricated using robotic gas metal arc welding (GMAW) and were subjected to a detailed characterization campaign. The results show significant scatter in the tensile properties as well as Charpy V-notch impact toughness data, which was then correlated to the microstructural heterogeneity and delta (δ) ferrite formation. Post-processing (austenitizing and tempering) treatments were developed and an ~70% reduction in the scatter of tensile data and a four-times improvement in the toughness were obtained. The changes in mechanical properties were rationalized based on the microstructure evolution during additive manufacturing. Based on these, an outline to tailor the composition of "printable" steels for tooling with isotropic and uniform mechanical properties is presented and discussed. [ABSTRACT FROM AUTHOR]