Enhanced mechanical performance of duplex stainless steels via dense core-shell nano-inclusions in-situ formed upon selective laser melting

In this study, with aid of selective laser melting (SLM) and minor Ti addition, we obtain a high density of core-shell structured nano-inclusions with an oxide core and a TiN shell in an S2205 DSS, where the high oxygen concentration originates from the severe oxygen contamination during the making of feedstock powders. These nano-inclusions can not only refine the microstructure by inhibiting the motion of austenite/ferrite interfaces upon the post-SLM annealing, but also contribute to a notable precipitation strengthening increment up to ∼230MPa. The current nano-inclusions strengthened DSS exhibits an attractive mechanical performance with a tensile strength of ∼910MPa and a total elongation of ∼52% yet non-deteriorative corrosion resistance, which has surpassed most of the reported 2205 DSSs. Our results provide a novel route for developing a wide range of nano-architectured SLM alloys with drastically enhanced properties.