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. This study innovatively suggests limiting residual deoxidizers content to address increased oxide inclusions and reduced toughness caused by high oxygen (up to 100 ppm) in additive manufacturing-processed maraging steel.