Influence of the Crystallographic Orientation on the Yield Strength and Deformation Mechanisms of Austenitic Grains in Metastable Stainless Steels Investigated by Spherical Nanoindentation

The mechanical behavior of a metastable stainless steel is studied by spherical nanoindentation, as a function of crystallographic orientation of its austenitic grains. The residual imprints are analyzed by electron backscattered diffraction (inverse pole figure, phase and geometrically necessary dislocation maps) and atomic force microscopy. Results showed that austenite grains with the most common crystallographic orientations display similar elasto-to-plastic transition, being the dislocation activity by the Frank-Read source the main deformation mechanism. However, the amount of dislocations generated during indentation testing strongly depends on the crystallographic orientation. No evidence of stress-induced phase transformation is observed.