Microstructure and corrosion behavior of a novel additively manufactured maraging stainless steel

This study aims to achieve a clear understanding of relationships between the anisotropy in the microstructure and corrosion behavior in a newly developed maraging stainless steel (Corrax® or SS CX) fabricated by the laser-powder bed fusion (L-PBF) technique. The focus was to compare the properties of the planes parallel (side) and perpendicular (top) to the building direction of the fabricated sample. Various electrochemical testing and multiscale electron microscopy techniques were used to investigate the microstructure and corrosion behavior of both planes. The results indicated that different thermal histories experienced on the top versus the side planes during the L-PBF lead to microstructural variations between the planes. A slight increase in the laths size, and the lower fractions of dislocation density and low angle grain boundaries, and plausibly the lower level of residual stresses on the side plane were found to contribute to the improved corrosion response of the side plane as compared to the top plane. •Martensite packets with a slight content of retained austenite were observed in L-PBF SS CX.•Nanometric round regions of inclusions containing Al and O were detected in L-PBF SS CX.•Anisotropic corrosion resistance of L-PBF SS CX was related to the differences in the level of residual stresses and the LAGBs density.•The plane parallel to building direction with larger grain size revealed higher corrosion resistance.