Fig. 1. Optical micrographs of 0.5 Mn (a) and 1 Mn (b) alloys after 0.5% HF etching for 40 s. The inset images are SEM micrographs of an unetched surface.

Fig. 2. Microstructures after hot deformation: (a) the base, (b) 0.5 Mn, (c) 0.75 Mn, (d) 1 Mn alloys, (e) an enlarged SEM image of 1 Mn alloy.

Fig. 3. The number density of dispersoids and DFZ area fraction in the different alloys after hot deformation.

Fig. 4. All Euler orientation maps of four experimental alloys after hot deformation: (a) the base, (b) 0.5 Mn, (c) 0.75 Mn and (d) 1 Mn alloys; the white lines indicate 2°-5°, the green lines indicate 5°-15°, and the black lines indicate >15°.

Fig. 5. Densities of the misorientation angle boundary of experimental alloys after hot deformation.

Fig. 6. All Euler orientation maps of the experimental alloys after different annealing times; the white lines indicate boundaries of 2°-5°, light green lines indicate boundaries of 5°-15°, and black lines show boundaries of >15°.

Fig. 7. Densities of the misorientation angle boundary of 2°-5° and over 15° in (a) the base, (b) 0.5 Mn, (c) 0.75 Mn and (d) 1 Mn alloys with different annealing time.

Fig. 8. Recrystallization grain size (a) and volume fraction (b) of experimental alloys at different annealing time.

Fig. 9. SEM microimages of the dispersoid evolution in the 1 Mn alloy before annealing (a) and after annealing at 500 °C for 2 h (b), 4 h (c), and 8 h (d). Bright field TEM images are inset in (a) and (c).

Fig. 10. Number density of dispersoids in 0.5 Mn, 0.75 Mn and 1 Mn alloys at different annealing time.

Fig. 11. Bright field TEM image of recrystallized grains in the 1 Mn alloy after 8 h of annealing.

Fig. 12. EBSD orientation map (a) and optical image (b) of the 1 Mn alloy after 8 h of annealing.

Fig. 13. A schematic of the recrystallization mechanism: (a) after deformation and before annealing, (b) formation of subgrains during annealing, (c) formation of recrystallized grains.