On the process of designing material qualification type specimens manufactured using laser powder bed fusion

• Published in: Materials & design Vol. 229; no. C; p. 111893
• Main Authors: Tekerek, Emine, Perumal, Vignesh, Jacquemetton, Lars, Beckett, Darren, Scott Halliday, H., Wisner, Brian, Kontsos, Antonios
• Format: Journal Article
• Language: English
• Published: United Kingdom Elsevier Ltd 01-05-2023; Elsevier
• Subjects: Additive Manufacturing; Defects; Design; In-situ monitoring data; Laser powder bed fusion; Microstructure; Quality control; Design; Laser powder bed fusion; Quality control; Additive Manufacturing; Microstructure; In-situ monitoring data; Defects
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2023.111893

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•A methodology for designing specimen geometries for laser powder bed fusion to be used for material qualification investigations is presented.•The methodology provides direct evidence on surface and volume effects caused when standard dog bone specimens are directly manufactured.•The specimen design methodology starts with thermomechanical simulations and is accompanied by a manufacturing process optimization approach.•In-situ melt-pool scale thermal measurements are combined with X-ray computed tomography analysis, as well as both profilometry and microscopy.•Process parameter, additive manufacturing machine and feedstock powder issues are discussed en route of optimizing specimen geometries.
Recent investigations involving specimens for material and process qualification related to the Laser Powder Bed Fusion (L-PBF) additive manufacturing (AM) method, point that microstructural quality and surface properties vary significantly based on feedstock material and process parameters. There is currently the need, therefore, to create systematic ways to design specimens for process and material qualification. This manuscript provides an approach to evaluate the effects on the as-built quality based on specific metrics for specimens produced by L-PBF. Surface quality, as well as micro- and sub-microstructures and defects are related to specific aspects of the L-PBF process. To accomplish this goal, a digital engineering approach was first developed to design geometries based on process simulations to account for mechanical and thermal process effects. A parametric AM fabrication plan was then chosen to produce statistically significant populations of AM parts. Moreover, on axis, melt-pool scale, in-situ monitoring data, collected during the AM process, was examined in conjunction with the formation of flaws. X-ray micro-computer tomography analysis was additionally used to characterize porosity levels. Finally, scanning electron microscopy (SEM) and electron back-scatter diffraction (EBSD), as well as surface profilometry were combined to correlate specific process parameters and conditions with microstructural and surface effects.