Research on the differences of mechanical properties between horizontal and vertical in al-cu alloy deposits fabricated by wire plus arc additive manufacturing

Al-Cu alloy made by arc fuse additive has excellent microstructure and properties, but the difference between transverse and longitudinal is the key factor limiting its application. In this experiment, Al-Cu alloy deposits with different Cu contents were formed by the wire + arc additive manufacturing (WAAM) process using Al-Cu welding wire with different Cu content. The microstructure and properties of the deposits, both intralayer and interlayer, were analyzed using metallography, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and tensile tests. The results showed that the interlayer content of Cu is higher than that in the intralayer. When Cu content in the deposit was 6.3% in the as-deposited state, there was an enhanced theta (Al2Cu) precipitate phase in the interlayer position. After T4 treatment, there were still theta phases with a size larger than 20 mu m, which were linearly distributed parallel to the accumulation layer. These theta phases led to lower mechanical properties in the vertical direction than in the horizontal direction, with a brittle fracture mode. When the Cu content of the deposit was reduced to 5.6% after T4 treatment, there were no large theta phases in the interlayer position. Furthermore, the mechanical properties of horizontal and vertical directions were consistent, and they had a ductile fracture mode. The Cu content in the deposit was the primary reason for the difference in mechanical properties between horizontal and vertical directions. Al-Cu alloy deposits with uniform mechanical properties in the horizontal and vertical directions can be obtained by controlling the Cu content, which has an important role in the application of this process.