Optimizing deoxidizer in maraging steel for additive manufacturing: Impact on oxide refinement and impact toughness

The high oxygen content in additive manufacturing powders (up to 100 ppm) significantly increases oxide inclusions and reduces toughness. This study explored various deoxidizers to control oxides in laser powder bed fusion-processed (L-PBFed) maraging steels. A strong deoxidizer (0.11 wt.% Al) forms 65 nm Al2O3 due to its high oxide formation temperature. A weak deoxidizer (0.24 wt.% Si, 0.21 wt.% Mn) produces low-melting-point SiO2-Cr2MnO4, which grows fivefold (135 nm) after heat treatment. Trace deoxidizer (Si/Mn/Al/Ti <0.01 wt.%) forms 45 nm TiO2-Cr2O3-SiO2 and achieves the highest cryogenic toughness (84 J). Controlling deoxidizer content is essential for optimizing L-PBFed maraging steels.