[16P-T20-01] Influence of Nanoprecipitation and Density on Micro-to-Macro Mechanical Properties of Additive Manufactured 18Ni-300 Maraging Steels
キーワード：Maraging steel, Additive manufacturing, Processing parameter, Microstructure, Mechanical properties
The 18-Ni 300 maraging steels with bulk cuboidal shape were fabricated by selective laser melting (SLM) to understand correlation between micro-to-macro mechanical properties and processing parameters. The as-built specimens fabricated under various laser power and scanning rate conditions were composed of α martensite phase with cellular arm spacing of 0.2 – 0.5 μm. The relative density of as-built specimens increased from 89.14% to 99.86%, depending on volume metric energy density (VED), laser power, and scanning rate. Micro Vickers hardness decreased with increasing VED and relative density in porous specimens and gradually increased in the full dense specimens with increasing VED. The contrast in micro hardness between porous and dense specimens was attributed to nanoprecipitation affected by intrinsic heat treatment during SLM. Compression test demonstrated that yield strength strongly correlated with relative density, gradually increasing to 1.13 GPa as the specimens reached full density.