Laser metal deposited steel alloys with uniform microstructures and improved properties prepared by addition of small amounts of dispersed Y2O3 nanoparticles

Steel is the most common engineering material used in additive manufacturing. In this work, 100-layers wall structures of 17Cr2NiSi steel alloys were successfully fabricated by laser metal deposition (LMD) in the presence of small dispersed amounts of Y2O3 nanoparticles without additional heat treatment. The effects of added amounts of Y2O3 nanoparticles on the microstructure, formability, microhardness, and tensile properties were all investigated. The results indicated a decline in many features, including formation of columnar and dendrite solidification structures, elongated grains in the build direction, pronounced crystallographic textures, and interlayer heat-affected zone. The reason for this was associated with the dissociation effect of Y3+ ions on dendrites by decreasing the melting point of the material, combined with the low-energy heterogeneous nucleation effect of Y elements on the grains through segregation into Si–Y–O particles. Meanwhile, minor amounts of Y element (