Powder Bed Fusion – Laser Beam (PBF–LB) is typically conducted in inert atmospheres. Replacing inert gases with more reactive ones initiates reactions between processing gas and material, which can be exploited for alloy design. In this work, the mechanisms during processing of in-situ oxide dispersion strengthened materials using a carbon dioxide (CO2) atmosphere via PBF–LB is studied. Pure Fe and Fe alloyed with 4.3 wt% Ti are manufactured under CO2, using a broad range of processing parameters, causing different melt pool lifetimes (tMP). The results show that the oxygen (O) content in the samples increases with volumetric energy density (EV) in as-built condition. O is observed in three forms in the materials – in slag layer, nanoparticles, and slag particles. The thickness of the slag layer, as well as the size and fraction of nanoparticles, increases with EV due to the prolonged time for O uptake. Suspended slag particles originating from the slag layer, are found in parts manufactured with insufficient EV. The distribution between nanoparticles, slag particles and slag layer is controlled by EV and consistent with measured O concentrations. These results show that the material-gas interaction in PBF–LB is controlled by tMP and thus by manufacturing parameters.      «

Powder Bed Fusion – Laser Beam (PBF–LB) is typically conducted in inert atmospheres. Replacing inert gases with more reactive ones initiates reactions between processing gas and material, which can be exploited for alloy design. In this work, the mechanisms during processing of in-situ oxide dispersion strengthened materials using a carbon dioxide (CO2) atmosphere via PBF–LB is studied. Pure Fe and Fe alloyed with 4.3 wt% Ti are manufactured under CO2, using a broad range of processing parameter...     »