Enhancing the mechanical behaviors of 18Ni300 steel through microstructural evolution in Electron Beam Powder Bed Fusion

Electron Beam Powder Bed Fusion (EPBF) offers unique advantages for processing 18Ni300 steel, including reduced contamination risks and higher energy absorption efficiency. This study systematically investigates the microstructural evolution and mechanical behavior of 18Ni300 steel fabricated via EPBF, focusing on key processing parameters such as electron beam current, scanning speed, and energy density. The results show that the density of EPBF-18Ni300 steel initially increases and then decreases with rising energy density, achieving a maximum density of 99.4 %. The optimal process parameters, identified as a beam current of 16.0 mA and a scanning speed of 4.5 m/s, yield tensile strengths and elongations of 1032.6 f 4.3 MPa and 12.98 f 1.1 % in the XOY direction, and 958.7 f 2.4 MPa and 16.5 f 0.9 % in the XOZ direction, respectively. These findings provide a foundation for optimizing EPBF processing strategies for 18Ni300 steel, enabling its broader adoption in highperformance applications across aerospace, automotive, and tooling industries.