Fig. 1 The bright field image a, the SAED pattern b, the dark field images c-e, the HRTEM image f and the overlap of inverse fast Fourier transform (IFFT) image and simulation f1 of the thermally processed IF steel under high pressure of 4 GPa. Black circle in a indicates the area where the SAED pattern was obtained, while the arrows in b indicates the diffraction spots used for dark field imaging

Fig. 2 The bright field image a, the SAED pattern b, the dark field images c-e, the HRTEM image f, the overlap of IFFT image and simulation f1; the bright field image g, the SAED pattern and Kikuchi diffraction pattern of V1 and V2 h, the HRTEM image i, and the overlap of IFFT image and simulation i1 [8] of the thermally processed IF steel under high pressure of 4 GPa. Black circle in a indicates the area where the SAED pattern in b was obtained, the arrows in b indicates the diffraction spots used for dark field imaging, and black circle in g indicates the area where the SAED pattern in h was obtained

Fig. 3 3D models of twinned variants V1 (red) and V2 (yellow) a, full-overlap projection b, part-overlap projection c, none-overlap projection d; 3D models of {112}?〈111〉?twins (blue) and matrix (red) e, none-overlap projection f, part-overlap projection g, and full-overlap projection h

Fig. 4 The (011)V1,V2 stereo-net projection of V1 (red) and V2 (blue) a; the (011)M and (0-1-1)T stereo-net projection of matrix (red) and twin (blue) b; where the dots are the zone axes and the dashed lines are the crystallographic planes