Microstructural Characteristics, Hardness, Wear Behavior, and Radiation Shielding Properties of L-PBF 18Ni-300 Maraging Steel Under Different Post-Processing Conditions

This study investigated the microstructural, mechanical, and radiation shielding characteristics of 18Ni-300 maraging steel specimens produced by selective Laser sintering and subjected to different heat treatment conditions. Three samples, denoted as S1, S2, and S3, were evaluated to clarify the effects of heat treatment on the phase distribution, grain morphology, elemental homogeneity, density, mechanical response, and radiation attenuation behavior.Microstructural observations showed that S1 exhibited a lamellar/dendritic multiphase structure, S2 had a more homogeneous and directionally arranged phase distribution, and S3 displayed a finer and more compact microstructure. EDS (X-ray analyses) confirmed that all samples were Fe-Ni-Co-Mo–based maraging steel alloys with minor compositional variations.The radiation shielding performance was assessed using theoretical calculations and Monte Carlo–based simulations through parameters including the mass attenuation coefficient, linear attenuation coefficient, half-value layer (HVL), mean free path (MFP), effective atomic number, equivalent atomic number, buildup factors, neutron transmission factor, and macroscopic effective removal cross section.The results showed that S1 provided the most favorable direct gamma-ray attenuation behavior, as indicated by higher attenuation coefficients and lower HVL and MFP values. In contrast, S2 exhibited lower energy absorption and exposure buildup factors, suggesting reduced secondary photon buildup. For neutron shielding, the investigated steels showed energy-dependent attenuation behavior, with S1 presenting comparatively better neutron attenuation among the steel samples.Overall, the results indicate that heat treatment can modify both the microstructural features and radiation shielding response of additively manufactured 18Ni-300 maraging steel. Rather than being considered a direct replacement for conventional shielding materials, this alloy may be regarded as a potential multifunctional structural material for applications requiring a combination of mechanical performance and radiation attenuation.