Microstructure/Mechanical Properties Relationship in High-Nitrogen Steel Obtained by Electron Beam Additive Manufacturing and Conventional Casting

A comparative study of the microstructure and mechanical properties of high-nitrogen steel, which was obtained by two different methods (conventional casting and electron beam additive manufacturing), was carried out. Independently on fabrication method, steel possesses two-phase structure of austenite and delta-ferrite, and the volume fractions and distribution of both phases depend on the fabrication method. Additively manufactured steel specimens have high strength characteristics and good ductility both in as-built state and after following solid-solution treatment. Despite the fact that the specimens produced by different methods possess different microstructure (coarse delta-ferrite and austenite grains in cast and solution-treated specimens and dendritic delta-ferrite/austenite microstructure in as-build specimens) their mechanical properties are very similar.