Toward a common laser powder bed fusion qualification test artifact

Abstract

Test artifacts have been used to evaluate additive manufacturing (AM) systems since the early 1990s with over 65 artifacts published to date. Due to the system agnostic approach to artifact design, principally focused on geometric accuracy, there has yet to be a widely adopted artifact for laser powder bed fusion (LPBF). To speed qualification of LPBF, a rapid method that quantifies impacts of process variables on part structure, properties, and performance is required. Using a list of design requirements developed from literature, build experience, and needs from several major roadmapping efforts, a test artifact was designed to evaluate geometry-specific microstructure, dimensional accuracy, residual stress, chemistry, surface integrity, powder removal, and distortion. The LPBF artifact includes: four sides for geometric feature accuracy and surface integrity analysis, indication marks for accurate sectioning for metallography, and additional features specifically designed to evaluate residual stress, powder removal, mechanical properties and distortion. The artifact is compact and designed to fit within a standard 50 mm metallographic mount with indication marks used to improve measurement repeatability and accuracy. Microstructure and anomaly population are quantifiable on features including overhangs, islands, thin features, channels, lattice structures and bulk areas representing different thermal histories. It is believed that this single test artifact can be used for many purposes, including optimization of LPBF input variables, qualification and more. Ongoing work is continuing to improve the artifact design, testing its implementation across LPBF platforms, and using the artifact to concretely define process sensitivity currently limiting standardization and adoption of LPBF due to costs associated with defining process windows in terms of qualification and certification. As part of this effort, the artifact described here forms the basis of the Global Test Artifact Data Exchange Program – a program designed and managed by the authors for the benefit of research to advance LPBF qualification efforts and help lead to more widespread adoption of LPBF (described in more detail at keck.utep.edu/GTADExP).