EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

With the growing industrial application of laser-based powder bed fusion (LB-PBF) there has been an increase in the amount of powder suppliers and powder grades. Despite similar atomizing technology, the quality of the powder feedstock can vary significantly between suppliers and batches in terms of powder flowability, impurities and powder surface chemistry. While high quality powder has its mandated uses, there are instances where high purity is not essential, allowing for lower cost powder to be considered. To date, the effects of powder properties, both physical and chemical, on the resulting mechanical properties of as-built components is still a topic that is not well understood. One of the contributing factors is the lack of relevant methods for evaluating powder spreadability rather than powder flowability. This study presents a review of different 316L powders that were produced using various atomization techniques. The physical powder properties were evaluated using powder metallurgical techniques, a powder rheometer and a revolving drum analyzer. Significant and correlative powder properties were highlighted, with a brief discussion on their applicability to powder spreading. Furthermore, the surface chemical state of the powder with regard to oxide composition was characterized and correlated to defects within the microstructure as well as to the mechanical properties of the as-built components. This review provides insight regarding the implication on potential changes in processability that different powder feedstocks can have and how different levels of e.g., oxygen can impact the final properties.