Microstructure evolution and mechanical properties of maraging steel 300 fabricated by cold spraying

For the moment, the additive manufacturing (AM) of maraging steel has attracted increasing attention due to its outstanding mechanical properties. As a recently-emerged AM method, the solid-state cold spray has been widely used to fabricate the metallic components. In this work, the maraging steel 300 (MS300) was fabricated by cold spray additive manufacturing followed by solution-aging treatment. Analyses based on X-ray computed tomography (XCT) and optical microscope (OM) show a densified microstructure with a minimum porosity of 0.168%. Phase analysis through XRD and EBSD exhibits that as-fabricated samples possess well-retained phase composition compared with feedstock material, and the solution-aging can lead to a highly martensitized microstructure in the prepared samples. EBSD analysis shows the ultrafine grain structure of as-fabricated samples indicating the formation of dynamic recrystallization during the CS deposition. Tensile tests show that through the cohesive diffusion and precipitation-strengthening, the solution-aging treatment can lead to a significantly improved tensile properties (ultimate tensile strength and elongation) with the fracture morphology featured by extensive dimples. The wear resistance of CS MS300 was also significantly improved through the precipitation-hardening. As a summary, this study demonstrates cold spray as a promising AM method can fabricate high-performance grade 300 maraging steel parts.