CFD Simulations for Additive Manufacturing

In laser powder bed fusion (LPBF) and directed energy deposition (DED) processes, studying the melt pool arising from laser melting of powder particles can provide significant insights into the build quality of these processes. High-fidelity computational fluid dynamics (CFD) models, which are based on a rigorous solution of the conservation equations, incorporate important underlying phenomena such as laser/electron beam with powder interaction, melt pool dynamics, phase change and solidification. Once calibrated against experimental data, these models provide insights into how process parameters such as beam power, scan speed, hatch spacing, powder size distribution, and powder compaction affect melt pool quality, porosity formation, balling defects, and microstructure evolution. Using such CFD models built in FLOW-3D AM, engineers and researchers can design better process parameter windows to influence and control laser-powder interaction, Marangoni convection, porosity formation, spatter formation and microstructure evolution. Case studies from the industry and academia highlighting the successful use of CFD models in developing process windows for different AM processes are discuss in this presentation. Topics on keyhole induced porosity in LPBF of Ti6Al4V, inter-layer void formation in selective electron beam melting, single and multi-layer track builds for DED processes and scan path influence on microstructure evolution are some of the topics that shall be discussed. CFD modeling can help our fundamental understanding of the LPBF and DED processes, ensuring that the melt pool is of ideal quality and defect-free, an important first step towards the wide-spread adoption of additive manufacturing. Such high-fidelity, multiphysics CFD models provide a framework to better understand AM processes from the micro-and meso-scales.