A newly developed, austenitic lightweight steel, containing a low-density element, Al, exhibits tensile
elongation up to 50% as well as high ultimate-tensile stress (tensile fracture at 1800 MPa) without
necking behavior. Electron backscatter diffraction analysis is carried out to investigate the orientation
dependence of the martensitic transformation in tensile testing to 30% strain at 323 K (25 °C). A pronounced γ-ε-α′ transformation is observed in o1114 and o1104∥TD (TD: tensile direction) γgrains. The α′-transformation textures is analyzed. Large misorientation spreads is seen in the
o1004∥TD γ-grains. Interestingly, twin-assisted martensitic transformation is detected in the
o1114∥TD followed by the twin boundary directly moving to a γ/α′ phase boundary. These phenomena
are related to a change of Schmid factor for different orientations of grains.