Effect of Process Parameters on Track Geometry and Porosity in Laser Direct Energy Deposition of High Strength Aluminum Alloy

Abstract

Laser Directed Energy Deposition (LDED) is a metal Additive Manufacturing (Metal AM) process that has attracted significant attention due to its ability to produce complex geometries with material properties comparable to cast and wrought parts. High-strength aluminum alloys especially 2xxx, 6xxx, and 7xxx series are difficult to fabricate using LDED process since these alloys are prone to hot cracking due to rapid solidification during the LDED process. The focus of this work is to evaluate the effect of LDED process parameters on track geometry and porosity of Al7075 powder. The effects of process parameters such as laser power, scan speed, and powder flow rate on track geometry and porosity, were investigated using a Formalloy LDED machine via L27 orthogonal array of experiments. Increasing the laser power resulted in an increase in bead width and wetting angle, whereas increasing the scan speed led to a decrease in bead height and wetting angle and a minor increase in width. The results also showed a linear increase in wetting angle and bead height with increased powder flow rate, while the width of the bead remained relatively constant. Furthermore, it was also observed that increasing the laser power to 750 W resulted in a decrease in the cross-sectional porosity of the bead due to the availability of sufficient energy density thereby facilitating proper melting. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.