Fig. 1. Schematic display of the setup for the in-situ synchrotron-based HEXRD experiments in reflection geometry under uniaxial loading.

Fig. 2. Microstructure of the (a) heat-treated sample in which the austenite (γ) exhibits a white tone and ferrite (α) exhibits a brown tone and (b) microstructure coated with white colloidal silica particles in which the austenite (γ) exhibits a bright tone and the ferrite (α) exhibits a dark tone.

Fig. 3. One-dimensional HEXRD pattern with the corresponding lattice planes of the austenite (γ) and the ferrite (α) of the peaks.

Fig. 4. Lattice strains of the (311) plane of austenite (γ) and the (211) plane of ferrite (α) as a function of the applied stress, where the different fonts of lines represent the tendency of the lattice strain.

Fig. 5. In-situ μ-DIC analyses of the strain in austenite (γ) and ferrite (α) in the sample in conditions of (a) undeformed stage, (b) the yielding of austenite, (c) the yielding of ferrite, and (d) both of the constituent phases undergo a certain amount of plastic deformation. The detail of strain evolution from (b) to (d) with red and white points, respectively, of the (e) red points numbered 1to 10, and (f) white points numbered 18 to 38 in.(a). The dotted lines in (e) and (f) correspond to the phase boundaries.

Fig. 6. Phase maps corresponding to the (b) undeformed sample, and the (c) to (e) microstructures in different red box areas on (a) a fractured sample, where austenite (γ) is shown as red color and the ferrite (α) is shown as green color; the (f) to (i) IPF maps, the (j) to (m) local misorientation maps, and the (n) to (q) GND density maps corresponding to the microstructures in the phase maps (b) to (e).

Fig. 7. Histogram of the local misorientation angle corresponding to the microstructures in the local misorientation maps of (a) Fig. 6j, (b) Fig. 6k, (c) Fig. 6l, and (d) Fig 6m.

Fig. 8. Typical microstructures of the samples under (a, b) 0.5 %, (c, d) 5%, and (e, f) 10 % strain observed based on the TEM bright field with the corresponding diffraction spectra on the corner of the figures.

Fig. 9. Schematic of the generation of GND caused by different mechanisms of the heterogeneous deformation behavior.

Fig. 10. TEM bright field image under the 200 two-beam condition of an austenite grain under a strain of 0.5 % with the diffraction pattern on the corner of the figure, denoting the piling up and the different activated slip plans of dislocations.