Structure and Mechanical Properties of Al–Cu–Mg–Si Alloy Prepared by Selective Laser Melting

The effect of the physical and additive-manufacturing (3D printing) characteristics on the structure and hardness of monolith and netlike articles fabricated from the Al–Cu–Mg–Si alloy by selective laser melting,—is considered. The structure and hardness of monolith samples, which were synthesized at the laser powers P = 100–200 W, scanning speeds V = 400–950 mm/s, and unchanged both laser beam spot diameters of 60 and 75 µm and powder layer thickness of 0.05 mm,—were compared and analysed. It has been found that the hardness of samples synthesized at Р = 200 W and V = 750–900 mm/s is 50HB10/250; the minimum hardness (less than 28HB10/250) is observed for the samples fabricated at V = 400 mm/s and Р = 100 W. Metallographic studies of the structure of samples exhibit the presence of defects, such as shrinkage voids, hot cracks, and non-melt powder particles. Experimental data indicating the correlation between the build geometry of netlike samples characterized by different filling levels (amount and configuration of the internal construction holes) and their dynamic properties measured by Hopkinson–Kolsky compression tests are obtained. It has been found that the decrease in the density (ρ = 2.44 – 1.19 g/cm³) and increase in the total fraction of hole area in the build plane and plane perpendicular to the build plane from 4 to 86% leads to the decrease in the dynamic mechanical properties, namely, the yield stress and ultimate tensile strength by 3 and by 4.7 times, respectively.