Effects of process interruptions on microstructure and mechanical properties of three face centered cubic alloys processed by laser powder bed fusion

Abstract

Many factors can influence the thermal history during laser powder bed fusion (L-PBF) that contribute to the microstructure and mechanical performance of produced components. These factors can include process parameters, geometry, feedstock characteristics, and more. In this work, we report on the effect that process interruptions have on the thermal history during L-PBF fabrication of simple geometries made out of three alloys of interest: AlSi10Mg, Inconel 718 and Inconel 625. Systematic experiments were carried out with programmed process interruptions lasting one hour and simulating a stop to refill the system with powder, or an unexpected power outage. Specimens produced through these experiments enabled studying microstructural differences using microscopy techniques, and the evaluation of tensile and hardness properties when compared to uninterrupted controls. The findings from this study indicate that there were no distinguishable microstructural differences from interrupted specimens and uninterrupted controls for all three materials. Also, although Inconel 718 interrupted specimens showed a slight reduction in ultimate tensile strength and elongation, these properties remained essentially unchanged for AlSi10Mg and Inconel 625. Although a more comprehensive study is still required that accounts for the effect of thermal post-processing and other factors, the results described here provide several observations of the potential effects of process interruptions, and the implications towards process validation and quality assurance of L-PBF.