Fig. 1. Schematic RT Q&P annealing cycles for 10Mn and 10Mn-2Si alloys. (a) Variation of partitioning temperature, (b) variation of partitioning time.

Fig. 2. Microstructures of 10Mn (a, b, c) and 10Mn-2Si (d, e, f) after partitioning at 300 °C for different periods. (a) 10Mn Q, (b) 10Mn Q&300P 4 h, (c) 10Mn Q&300P 16 h, (d) 10Mn-2Si Q, (e) 10Mn-2Si Q&300P 4 h, (f) 10Mn-2Si Q&300P 16 h (γ: austenite, α´: α´-martensite, α´T: α´-tempered martensite). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

Fig. 3. Precipitation in (a, b, c) 10Mn Q&300P 16 h and (d, e, f) 10Mn-2Si Q&300P 16 h. (a, d) Bright field images, (b, e) dark field images using (0$\bar{1}$12) epsilon carbide reflection and (c, f) electron diffraction patterns.

Fig. 4. (a, c) Engineering stress-strain curves and (b, d) true stress (solid lines) and strain hardening rate (SHR, dotted lines)-true plastic strain curves after partitioning at different temperatures for 30 min. (a, b) 10Mn, (c,d) 10Mn-2Si. (e) Yield strength (YS), ultimate tensile strength (UTS), and (f) total elongation with respect to partitioning temperature.

Fig. 5. (a, c) Engineering stress-strain curves and (b, d) true stress (solid lines) and strain hardening rate (SHR, dotted lines)-true plastic strain curves after partitioning at different temperatures for 30 min. (a, b) 10Mn, (c, d) 10Mn-2Si. (e) Yield strength (YS), ultimate tensile strength (UTS), and (f) total elongation with respect to partitioning time.

Fig. 6. Carbon concentrations of austenites in 10Mn and 10Mn-2Si with respect to (a) partitioning temperature and (b) partitioning time at 300 °C.

Fig. 7. Schematic of microstructure evolution during partitioning.

Fig. 8. Evolution of austenite fraction during tensile deformation in (a) 10Mn and (b) 10Mn-2Si.

Fig. 9. Stacking fault energy of austenite in 10Mn and 10Mn-2Si as a function of (a) partitioning temperature and (b) partitioning time at 300 °C.

Fig. 10. Austenite in 10Mn Q&300P 16 h after tensile deformation until 0.15 strain. (a) Bright field image of austenite, (b) dark field image of austenite using (200) austenite reflection, (c) dark field image of twin using ($\bar{1}$1$\bar{1}$) twin reflection and (d) electron diffraction pattern.

Fig. 11. Grain area distribution of the retained austenite in 10Mn Q and 10Mn-2Si Q. (a) In full range, and (b) those smaller than 0.9 μm.

Fig. 12. (a) Evolution of relative martensite fractions during tensile deformation in 10Mn and 10Mn-2Si, which were fitted with Eq. (4). (b) Acquired k values with respect to stacking fault energy.