Effect of Bimodal Size Distribution on the Behavioural Properties of Powders Used in the LPBF Process

The adoption of the Laser Powder Bed Fusion (LPBF) process faces challenges due to a low productivity and high powder costs. Improvements in productivity can be achieved by increasing the laser power and the layer thickness. The present work explores an alternative approach by investigating the use of coarser particle size distributions in conjunction with thick powder layers. This approach potentially allows the valorisation of currently unexploited powder fractions in the LPBF process. In this work, blends of AISI 420 stainless steel powders are characterised in terms of their compaction dynamics and flow properties. The results obtained show that different levels of cohesion and compaction rate are found depending on the size ratio, the absolute size of the fine powder and its fraction. This work provides guidance for the selection of powder blends and opens up the possibility of their use in the LPBF process.