Influence of Heat Treatment on the Microstructure and Properties of 2319 Aluminum Alloy Produced by Wire Arc Additive Manufacturing

A single-layer wall specimen of 2319 aluminum alloy was fabricated by the wire arc additive manufacturing (WAAM) technique through layer-by-layer welding, and it was then subjected to solution treatment and aging treatment. This study investigated the changes in the microstructure, mechanical properties, and corrosion resistance of the materials after deposition and heat treatment. The results show that in the as-deposited microstructure, there is a second phase in the form of a network structure. In addition, the number of impurity phases is large, and their sizes are relatively big. After solution treatment, most of the second phase is dissolved, and the remaining impurity phases are mainly the θ phase, with relatively small sizes. After subsequent aging treatment, a fine and dispersedly distributed second phase is formed in the dendrites. Compared with the as-deposited state, the number of secondary phases in the matrix after heat treatment is significantly reduced, and the distribution is more dispersed, which improves the mechanical properties and corrosion resistance of the material. After heat treatment, the tensile strengths in the horizontal and vertical directions of the alloy reach 362 MPa and 339 MPa, respectively, which are increased by 60.7% and 63.8% compared with the as-deposited state. However, the plastic deformation ability of the material after aging treatment decreases to a certain extent.