In-Situ Monitoring for Defect Identification in Nickel Alloy Complex Geometries Fabricated by L-PBF Additive Manufacturing

Abstract

Published literature shows defect formation during laser powder bed fusion additive manufacturing (AM) of nickel base superalloys are sensitive to alloy chemistry, processing conditions, and geometry. In this work, ability to detect spatial distributions of defects is explored using in-situ monitoring of thermal signatures and surfaces. Simple and complex geometrical components were fabricated with CM247-LC® powder in an AM machine outfitted with optical and thermal sensors. The spatial and temporal variations of thermal signatures (peak intensity, decay, and number of gyrations), as well as, layer-by-layer optical images were analyzed. The observed thermal signatures were also verified with an analytical model for layer-wise heat transfer simulation that is sensitive to laser raster scan strategies. The cross-comparison data with reference to defects, obtained by X-ray tomography, were correlated with in-situ observations.