To ensure consistent quality of additively manufactured steel parts, it is advantageous to identify alloys which can routinely meet performance criteria while being robust to process changes. Toward this end, multiple steel compositions produced by blending AF-9628 steel with pure iron powders were deposited via laser-directed energy deposition (L-DED) and analyzed for process sensitivity and mechanical properties. Studied mixtures ranged from 100% to 10% AF-9628 by mass. Considering thermal features relevant to L-DED, JMatPro simulation software was used to roughly predict material properties, phase fractions, and sensitivity to cooling rate, preheat temperature, and tempering conditions. Test samples were deposited using a variety of parameter sets, and the sensitivity of as-built hardness to processing conditions was evaluated for each composition. Further investigation of tensile property sensitivity was conducted on a single composition of interest, and results were compared to those of unmixed AF-9628.