Changes in the mechanical properties of selective laser melted maraging steel 300 induced by exposure to a simulated marine environment were investigated. Maraging steel samples were printed in three orientations: vertical (V), 45◦ (45), and horizontal (H) relative to the print bed. These were tested as-printed or after heat-treatment (490 ◦C, 600 ◦C, or 900 ◦C). One set of specimens were exposed in a salt spray chamber for 500 h and then compared to unexposed samples. Environmental attack induced changes in the microstructural features and composition were analyzed by scanning electron microscopy and energy dispersive spectroscopy respectively. Samples printed in the H and 45◦ directions exhibited higher tensile strength than those printed in the V direction. Corrosion induced reduction in strength and hardness was more severe in specimens heat-treated between 480 ◦C and 600 ◦C versus as-printed samples. The greatest decrease in tensile strength was observed for the 45◦-printed heat-treated samples after exposure. A comparison between additive and subtractive manufactured maraging steel is presented.
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