Spatters deposition on Inconel 718 laser powder bed fusion manufacturing

In laser powder bed fusion (PBF-LB), the detrimental effects of by-products need attention when defining a manufacturing process. One of the by-products able to modify some parts' attributes is called spatters, which consists of metal particles ejected during lasermaterial interaction throughout the laser trajectory. Spatters have different attributes from the virgin powder, like dimensions and oxidation level, that can change material properties and part integrity. These spatters can lead to mechanical property degradation when remelted in the part. Moreover, the build chamber gas flow configuration can play a significant role in dictating how spatter deposits along the build platform. The present study aimed to experimentally map the spatters' deposition behaviour on the build platform of a PBF-LB machine chamber when manufacturing Inconel 718 parts. To this end, the manufactured parts were centralised in the front position of the build platform near the gas inlet, while the middle and back regions were used for collecting the deposited powder and spatters. The powder samples were then examined using optical measurement equipment, and the acquired images were analysed to extract quantitative metrics of spatter deposition based on defined criteria for spatters' identification. An influence of the gas flow direction on the powder deposition along the build platform was verified. These quantitative measurements highlight the role of the gas flow behaviour in carrying these by-products along the build chamber, providing experimental indications of where they depose under the studied manufacturing conditions. Finally, understanding the spatters' deposition behaviour can be considered to better deal with by-product contamination during PBF-LB manufacturing with remarkable consistency.