Additively manufactured martensitic stainless steel components can combine complex geometry with superior mechanical and corrosion performance. In this work, the mechanical performance of AISI 410L processed by laser directed energy deposition (L-DED) additive manufacturing using previously optimized parameters is assessed. Microstructure, hardness, tensile strength, and Charpy impact toughness are evaluated in the as-built and heat-treated conditions. Four heat-treatment routes are investigated: (I) austenitization and water quenched, and austenitization, water quenched, and tempered at (II) 300, (III) 450, and (IV) 600 °C, followed by air cooling. The results show that, for tempering temperatures up to 450 °C, the hardness, yield strength, and ultimate tensile strength show an increasing trend when compared with the as-built condition and reference commercial standard (annealed AISI 410) because of microstructure refinement induced by recrystallization. Tempering at 600 °C, on the other hand, enhances the ductility of the specimens, accounting for an increased deformation until fracture and superior Charpy impact toughness. In summary, this work demonstrates that, for all tested conditions, the tensile strength of the AISI 410L additively manufactured by L-DED outperforms that of the standardized commercial AISI 410 martensitic stainless steel, and that post-processing heat-treatments can be used to further enhance toughness and ductility, making it even more competitive.

The corrosion resistance of Inconel 625 processed by L-DED additive manufacturing using virgin and reused powders was investigated to optimize the cost-effectiveness of the process. Samples were manufactured under a controlled argon atmosphere. Feedstock and samples were characterized by optical and scanning electron microscopy, energy-dispersive X-ray spectroscopy, and rheology analysis. Corrosion resistance was investigated by cyclic polarization and electrochemical impedance spectroscopy in NaCl 3.5% media. Rheology accused a slight decrease in powder flowability with reuse, but no further appreciable powder degradation was observed. Samples developed a dendritic microstructure with Mo- and Nb-rich Laves phase in the interdendritic region. Samples processed with reused powder were found to have a high content of oxides, which accounted for a slightly inferior impedance and reduced the charge transfer resistance by nearly 50%. Specimens had an overall similar cyclic polarization, with the specimen processed with virgin powder having a slightly superior performance, with a 60mV more noble E_corr and higher R_p, but similar I_corr. Samples presented uniform and pitting corrosion mechanisms, with pits being preferentially located in the Mo-depleted dendritic regions. In summary, the reuse of Inconel 625 powder processed under argon-controlled conditions was not considered to be significantly detrimental to the alloy corrosion resistance.