|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Additive Manufacturing: Building the Pathway towards Process and Material Qualification
||A-74: Stainless 316L Powder Recyclability and Oxygen Pickup as Applicable to Selective Laser Melting (SLM)
||Daniel Galicki, Fred List
|On-Site Speaker (Planned)
In laser powder bed additive manufacturing processes, feedstock materials are often recycled after each build. This recycling decision assumes minimal pick up of gases like oxygen by un-melted metallic powders. Currently, a knowledge gap exists in the fundamental understanding of how the powder size distribution, morphology, and chemistry changes resulting from re-use affect the subsequent component properties and the flowability of the powder. Initial findings from experimental trials with stainless steel 316L have indicated significant oxygen pickup in molten material ejected from the powder bed surface (0.186 wt%) compared to feedstock powder (0.032 wt%). X-Ray diffraction analysis has also confirmed the presence of a magnetic ferritic (BCC) phase intermixed with the predominantly austenitic (FCC) phase within the re-solidified ejecta material. Excessive oxygen pickup by recycled powder may affect the pool shape and molten metal convection of the micro-weld and initiate the precipitation of unwanted oxides within the as-built metal part.
||Planned: Supplemental Proceedings volume