The role of process parameters and printing position on meltpool variations in LPBF Hastelloy X: Insights into laser-plume interaction

Abstract

Meltpool dimensions play a pivotal role in defining the defects and microstructure state of Laser Powder Bed Fusion (LPBF) builds. Therefore, it is crucial to investigate variations in meltpool geometries under different process conditions. In this work, we fabricated single tracks of LPBF Hastelloy X (HX) alloy under 36 printing conditions and examined the corresponding cross-section meltpool dimensions at two locations across the build platform. This investigation demonstrates the impacts of laser power, scan speed, powder layer thickness, and printing locations on resultant meltpool dimensions. As expected, we observed that meltpool dimensions increase as laser power increases or scan speed decreases. It was also concluded that thicker powder layers lead to wider and shallower meltpools due to reduced laser energy penetration into the solid beneath the powder layer. Additionally, the meltpool dimensions show variations dependent on deposition locations due to the different levels of interaction of the laser and its induced vapor plume, resulting in shallower and wider meltpools. These findings provide a systematic understanding of meltpool dimension variations across various process conditions for LPBF HX alloy, which ultimately offer insights into the formation of defects and microstructure features.