High-throughput method for alloy development towards hydrogen applications using directed energy deposition

This study presents a high-throughput alloy development methodology combining in-situ powder mixing with directed energy deposition (DED) to rapidly synthesize compositional variants within a predefined design-of-experiments matrix. Fe–Cr–Ni and Fe–Cr–Ni–Mo alloys were selected as representative austenitic stainless steel systems for hydrogen-related applications, where alloy design and austenite stability are key to mitigating hydrogen embrittlement. The approach enables efficient fabrication of multiple compositions and streamlined sample preparation using a custom designed sample pallet for semi-automated characterization. Microstructural analysis showed that laser power strongly affected compositional homogeneity: higher power reduced unmelted chromium particles and improved elemental distribution, although complete elimination remained difficult. All alloys exhibited predominantly face-centered cubic austenitic structures with pronounced crystallographic texture, while minor ferritic signals were detected in some DED samples. Indentation-based stress–strain measurements revealed lower hardness and strength in the in-situ alloyed materials compared to commercial 1.4404 stainless steel, reflecting compositional and microstructural differences. Hydrogen charging demonstrated composition-dependent behavior, with hydrogen-induced strengthening in 1.4404 sheet and moderate strength degradation in most DED alloys. Overall, the methodology enables accelerated alloy screening and elucidates key processing–microstructure–property relationships relevant to hydrogen-resistant stainless steel design.