Iron-based Metal Matrix Composites (IMMCs) were produced by additive manufacturing (AM) using L-PBF and DEDp processes. For L-PBF, spherical steel powder particles were grafted with 3.2 wt.% nanometric TiC to provide good homogeneity of chemical composition and reinforcement distribution. Rheological and density tests show an increase of the powder flowability with grafted TiC nanoparticles compared to the base powder. The analysis of single L-PBF tracks shows high amount of spatter and lower wetting angles for grafted powder. A low porosity rate of 0.26 vol. % was obtained with L-PBF composite grafted powder. DEDp was performed with a premixed composite powder containing the same weight fraction of TiC that L-PBF.  For DEDp, the analysis of powder stream indicates that reinforcement particles must be larger than 10 µm in diameter to ensure a consistent powder stream. Unmelt TiC particles were limited to 0.4 wt. % with single track study. On 3D parts built by L-PBF, the hardness reaches 600 HV and is constant in the entire 4 mm build height. For DEDp, hardness varies from 350 HV at the bottom of the part to 600 HV on the top layer. A finer microstructure was observed on L-PBF-processed parts compared to DEDp-processed, with a better homogeneity in reinforcements distribution, shape and geometrical accuracy of parts.

Keywords: Steel matrix composite; DEDp; PBF-LB.