Honors College Theses

Effects of Varied Oxygen Levels, Laser Powers, and Scanning Speeds on Manufactured Components by Laser-Based Powder Bed Fusion

Amelia McNamee, Georgia Southern University


This project addresses the effects of oxygen concentration, laser power, and scanning speed on the melt pool geometry of laser-based powder bed fusion (L-PBF) additively manufactured components. A parametric analysis using the substrate alone was conducted to determine a range of desirable laser powers and scanning speeds. The parameter with the more significant effect will be decided upon based on the depth-to-width ratios (D/W) of the resultant laser weld bead. A range of oxygen levels and scan speeds was selected for the next phase. These samples were then be analyzed for depth-to-width ratios. It was expected that higher oxygen concentrations will result in larger depth-to-width ratios due to the reversal of the Marangoni convection and that lower scan speeds and higher laser powers would yield larger depth-to-width ratios due to increased input energy density. It was determined that increased oxygen levels, up to approximately 1.5% oxygen, slower scanning speeds, with a minimum of approximately 300 mm/s, and higher laser powers yielded increasing D/W ratios. Additionally, the similarity between average and median D/W ratios, along with small standard deviations, indicate that the data exhibits acceptable accuracy and precision.