Orientation-dependent indentation modulus and yielding in a high Mn twinning-induced plasticity steel

The dependencies of indentation modulus and yielding behavior on the crystallographic orientation in a high Mn twinning induced plasticity (TWIP) steel were systematically investigated by spherical nanoindentation. A series of nanoindentation experiments revealed that the values of the plane-strain modulus and maximum shear stress at the pop-in increased with an order of (0 0 1), (1 0 1), and (1 1 1) grains. Mechanical twins were only observed in the indented (0 0 1) grains, as was expected from Schmid factor for twinning in fcc crystals.

► Nanoindentation experiments of (0 0 1), (1 0 1), and (1 1 1) oriented grains of twinning induced plasticity steel.
► Plane-strain modulus and load at excursion increased with an order of (0 0 1), (1 0 1), and (1 1 1).
► The load at excursion increased with decreasing the Schmid factor for compressive deformation.
► Mechanical twinning took place only in (0 0 1)-oriented grains.