Abstract Scope |
Laser Powder Bed Fusion (LPBF) additive manufacturing (AM) has the distinct advantage of producing complex parts with fine feature resolution due to the high energy density power source and fine powder feedstock. As with any other joining or manufacturing process, a common set of user-defined process parameters, mainly laser power, scanning speed and strategy, are optimized to promote printability and part performance in service. This work seeks to inform the effects and opportunities LPBF users may experience by moving away from standard usage of Argon and Nitrogen as process gases. Building upon extensive literature regarding other welding and joining processes, mainly laser welding, efforts to fill the gap in such knowledge for the LPBF process include the manufacture and analysis of thin-wall structures, as well as implementation of modelling and fume analysis techniques. As these methodologies provide a comprehensive analysis of the fundamental laser-material interactions under varying atmospheric conditions, differences in solidification behavior and part morphology are identified and explained through differences in convective heat transfer and laser beam obscuration. As such behaviors are quantified, they are to be implemented into modelling efforts seeking to expand the range of conditions tested in a more time and resource efficient manner. Results from this work are expected to not only include valuable characterization of the LPBF process for future development, but also to inform the expansion of capabilities of existing LPBF systems currently in service. In totality, the final impact on the welding and joining community will be an understanding on how to optimize process gases for LPBF as one would for nearly every other fusion-based manufacturing process. |