Integrated Alloy Design And Additive Manufacturing Of Low-Density Fe-Mn-Al-Ni-Cr-C Steel: Gas Atomization, Laser Directed Energy Deposition, And Microstructure-Property Relationships

Abstract

This study introduces a new low-density steel (LDS) with an austenitic matrix strengthened by a stable, finely dispersed B2 intermetallic phase to optimize strength and toughness. The alloy was produced through vacuum induction melting and casting, followed by gas atomization to create spherical powders suitable for additive manufacturing (AM). Powder characterization revealed a narrow size distribution, high sphericity, dendritic surfaces, and minor Mn–Al segregation, which is consistent with rapid solidification. Bulk specimens were fabricated via Directed Energy Deposition at laser powers of 150 W and 180 W. Microstructural analysis using optical microscopy, SEM, and EBSD revealed near-full density with minimal porosity; slightly more unmolten particles were observed at lower power. Microstructures consisted of ~80% austenitic matrix and ~20% BCC|B2 phase. Indentation-based mechanical analysis indicated hardness (~410 HV), corresponding to ~1250 MPa yield strength, ~1350 MPa tensile strength, and ~23% ductility. These results demonstrate the viability of B2-strengthened LDS for AM.