Microstructure and Mechanical Properties of 2319 Al-Cu Alloy Fabricated by Laser-Metal Inert Gas Hybrid Additive Manufacturing

The microstructure and mechanical properties of 2319 Al-Cu alloy fabricated by laser-MIG hybrid additive manufacturing (LAHAM) were investigated. Compared with wire-arc additive manufacturing (WAAM), the laser induction could make the arc more concentrated, more stable, less sputtering and higher final forming accuracy. The surface of the specimen fabricated by LAHAM is smoother than the one fabricated by WAAM. The microstructure in WAAMed specimen is columnar grain and changed to dendrite grain in LAHAMed specimen. The addition of laser makes the Cu distribution uniform in LAHAMed specimen than the one in WAAMed specimens. The tensile strength, elongation and microhardness of WAAMed specimens are 240.3 MPa, 9.8% and 92.4 HV, respectively. After adding laser, the tensile strength, elongation and microhardness are 271.4 MPa, 11.6% and 97.0 HV, respectively, which are 12.9% and 18.3% higher than those fabricated by WAAM. The mechanical properties and elongation improvement are attributed to the grain refinement and precipitation strengthening effect of dispersed granular eutectic.