The influence of laser directed energy deposition (DED) processing parameters for Al5083 studied by central composite design

Abstract

Laser directed energy deposition (DED) of high-quality structural Al-based alloys is challenging due to the inherent physical and thermal properties of the Al powder feedstock. Therefore, an in-depth understanding of the influence of the applied processing parameters on the characteristics of the deposited material is paramount if one is to attain optimal performance. The objective of this study is to investigate the influence of the dominant processing parameters (laser power, scan speed, powder mass flow rate (PMFR), and hatch spacing) on the geometrical characteristics (track's height and dilution) of Al5083 double tracks fabricated using Laser Engineered Net Shaping (LENS®). Central composite design (CCD) response surface methodology (RSM) was utilized to study the influence of the varied processing parameters and their interactions and to develop an empirical statistical prediction model for the studied responses. The results reveal that the applied PMFR has a strong influence on the deposited track's height (positive) and dilution (negative). The laser power at the first-order factor shows a weak influence for both studied responses. However, the interaction between the laser power and the hatch spacing shows significant effects on the track's height and dilution. The microstructure and microhardness of the as-deposited Al5083 double tracks are also discussed, as proxies to the anticipated performance of the deposited material.

Keywords

• Additive manufacturing (AM)
• Directed energy deposition (DED)
• Laser Engineered Net Shaping (LENS®)
• Aluminum alloys
• Central composite design (CCD)
• Response surface methodology (RSM)