Acoustics for in-process melt pool monitoring during metal additive manufacturing

Abstract

Intrinsic to most metal additive manufacturing (AM) processes are melt pools generated from directed energy sources like lasers. Melt pools are critical as they function to join powder layers to previous layers during the process. Their criticality extends deeper as most porosity in AM parts stems from melt pool behavior while melt pool solidification dictates the parts’ microstructure. Significant breakthroughs in metal AM are severely hindered by the lack of access to experimental tools to study melt pools and modeling that do not fully capture the complex physics. Thus, melt pool related defects are often difficult to predict in occurrence and location while determining optimal process parameters to eliminate defects is extremely challenging and costly. Furthermore, the many exciting opportunities such as realizing new AM alloys, developing gradient materials/structure, and tailoring microstructure to intended applications are possible only with further understanding of melt pool behavior. With these clear needs, in-process acoustics have been proposed as plausible experimental tools for studying melt pool behavior. This presentation will provide an overview of the current activity in this area in addition to the specific needs the acoustics community can potentially address.