The influence of aluminum alloying on microstructure, phase composition, and mechanical properties of chromium-nickel steel obtained by electron-beam additive manufacturing

The influence of aluminum alloying on microstructure, phase composition, and mechanical properties of the AISI 321 austenitic stainless steel produced by a dual-wire electron-beam additive manufacturing is investigated. The billets with 5 and 10 wt.% of Al were produced using an electron-beam additive manufacturing process with simultaneous deposition of AISI 321 and aluminum wires. It has been shown that the AISI 321 steel alloyed with 5 wt.% of aluminum has duplex microstructure (ferrite + austenite) and demonstrates higher strength characteristics in comparison with aluminum-free steel. Specimens with tensile axis lying in the plane perpendicular to the grown direction of the additively produced billet is characterized by satisfactory plasticity (25–35%), and the specimens whose axis coincides with the grown direction of the billet undergo brittle fracture due to the possible presence of finely dispersed particles of intermetallic compounds at interphase or interlayer boundaries. Steel alloyed with 10 wt.% of aluminum has a single-phase ferritic structure, and steel specimens undergo brittle fracture regardless of their orientation relative to the grown direction of the additively produced billet. The results obtained show that for dual-wire electron-beam additive manufacturing technology is perspective for obtaining a light-weight Cr–Ni steel with high strength properties.