Deformation-based additive manufacturing of 7075 aluminum with wrought-like mechanical properties

Abstract

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.

Keywords

• Additive manufacturing
• AA7075
• Solid-state processing
• Strength
• Ductility