Mechanical Stability of Retained Austenite and Texture Evolution in Additively Manufactured Stainless Steel

We employed two additive manufacturing (AM) strategies perpendicular to each other in AM stainless steel. In contrast to the vertically-built strategy, the horizontally-built one imposed higher tensile strength and ductility due to distinct transformation-induced plasticity (TRIP) behavior and a tailored initial texture oriented more favorably for deformation texture. We applied the direct-aging-treatment without solid-solution to retain unique AM microstructure and retained austenite (RA), which enhanced yield strength (+ 60.2%), tensile strength (+ 41.2%), and ductility (+ 81.2%). This effective strengthening by the direct-aging-treatment effectively increased the stability of RA delaying the onset of TRIP. This is because RA grains possessed relatively homogeneous chemical composition by aging and are effectively suppressed by a harder neighbored precipitated-martensitic matrix despite the increase of stacking fault probability. Our findings offer a promising paradigm for tailoring properties of texture-controlled AM steels with the aging strategy and advance a fundamental understanding of the intrinsic deformation behavior of AM metals.