Assessing powder processability and melting behavior in powder-bed fusion additive manufacturing

In this study, the effects of powder characteristics on powder bed properties and the subsequent impacts of these properties on melt solidification were investigated. To this end, eight stainless-steel powders with varying characteristics were examined. The process maps generated for these powders were also assessed, focusing on their melt-solidification behavior and their implications for buildability (i.e., product quality). The build density distribution across the process map exhibited substantial variations. This variability was primarily attributed to the distinct melting behaviors associated with the unique characteristics of each powder. Both the real powder layer thickness of the powder bed and the melt-pool depth could be estimated by performing numerical simulations. Powder characteristics, particularly particle size and particle-size distribution, had significant effects on the achieved build density. Considering these findings, we introduced a new parameter zR/D90, which is determined by the powder characteristics and real powder layer thickness. Consequently, zR/D90 emerged as a valuable parameter for predicting the buildability of the powder. Therefore, this parameter can be noted as a reliable predictor of powder buildability, thereby providing guidelines for manufacturing parts with few defects.