Introduction of Cr steels to additive manufacturing using an innovative alloying approach - Challenges and Potentials

This study introduces martensitic Cr steels into additive manufacturing (AM) and provides first important findings for its PBF-LB/M processing. The comprehensive approach covers the entire process chain, including alloy modification, powder production, additive manufacturing, and microstructural characterization. Nitrogen (N), as an interstitial element soluble in iron, plays a central role in this strategy, offering economic and sustainability benefits during powder production while improving the PBF-LB/M-processability and performance of the final components. The atomizing gas N₂ was employed in vacuum induction gas atomization (VIGA) to facilitate direct alloying with N in the powder production process. A thermodynamic calculation-based alloying adjustment of the base alloy resulted in an increased N concentration of approximately 0.17 mass% in the powder. Consequently, electron backscatter diffraction (EBSD) and X-ray diffraction (XRD) studies demonstrate a notable increase in austenite content in the PBF-LB/M state. This finding aligns with thermodynamic predictions regarding the impact of N on austenite stability, reducing the propensity for cold cracking.