Effect of post-deposition heat treatment on laser-TIG hybrid additive manufactured Al-Cu alloy

Abstract

After solution + artificial aging treatment (T6 heat treatment) of 2219 aluminum alloy fabricated by laser-tungsten inert gas (TIG) hybrid method, more interestingly, we found that both the strength and elongation were improved. The strengthening mechanism has been analysed in details. Results showed that each layer was divided into the arc zone (AZ) and laser zone (LZ) before and after heat treatment. After T6 heat treatment, the columnar crystal grain morphologies remained the same as the as-deposited condition, while the microstructure presented a strong {001} texture along the building direction. Moreover, the high density of the needle-shaped θ″ phases were uniformly precipitated after artificial aging. Distinct grain morphology, increased the mass fraction of Cu in the Al matrix, and nano-precipitates in the AZ and LZ improved the tensile properties, which exhibited a yield strength of 242.1 ± 19.6 MPa, an ultimate tensile strength of 407.1 ± 31.1 MPa, respectively.

Keywords

• laser-tig hybrid additive manufacturing
• heat treatment
• high strength aluminum alloy
• microstructure evolution
• strengthening mechanism