Effect of SiC addition on processability of AISI S2 tool steel for laser powder bed fusion

Abstract. Laser Powder Bed Fusion (LPBF) of metallic alloys allows to achieve complex shape parts with innovative properties. However, the commercial availability of powder for LPBF is still limited, thus restraining the development of new alloys. To overcome this shortcoming, mixing different powders allows to tailor the chemical composition, although affecting the LPBF process. Indeed, to achieve a fully dense and defect-free part a proper melt pool must be generated during the LPBF process, in order to ensure good overlapping between each track and layer. Melt pools can be described as conductive or key-hole like, promoting the appearance of process-induced defects such as lack of fusion or key-hole porosities. Processing a mixture of several powders by changing the amount of one constituent can affect the type of melt pool generated during the process, thus shifting the process map. In this work, AISI S2 tool steel powders are enriched with 5 and 10% (in volume) of Silicon Carbide (SiC) and processed by LPBF. The effect of SiC on the processability is discussed for different volumetric energy density (Ed). Defects within cross sections are characterized and quantified, as well as the melt pool depth and morphology.