Fig. 1 True stress-strain curves at different deformation temperatures and strain rates: a 0.01 s-1, b 0.1 s-1, c 1 s-1, d 10 s-1, e 30 s-1

Fig. 2 Dependence of characteristic stresses on: a deformation temperatures at a strain rate of 1 s-1, b strain rates at a deformation temperature of 1000 °C

Fig. 3 Dependence of the peak stress on: a strain rates, b deformation temperatures, c the Zener-Hollomon parameters

Fig. 4 Initial microstructure of the specimen before hot compression: a SEM image, b combined image of grain boundary map and color code phase map measured by the EBSD, with the austenite (fcc) shown in blue and δ-ferrite (bcc) in red

Fig. 5 CSLM in situ observations of the tested steel at a 0.03 s and 24.2 °C, b 441.5 s and 1107.1 °C, c 545.5 s and 1099 °C, d 618.7 s and 1050.1 °C, e 679.9 s and 1000.0 °C, f 739.5 s and 950.0 °C, g 797.7 s and 900.0 °C, h 858.6 s and 850.2 °C, i 917.6 s and 800.3 °C

Fig. 6 Dependence of the volume fractions of austenite and δ-ferrite on the temperature during the cooling process in CSLM testing

Fig. 7 EBSD analysis (showing austenite in blue, δ-ferrite in red, HABs in black solid lines, and MTs in yellow solid lines) of the duplex microstructure of the specimens deformed at: a 0.01 s-1 and 850 °C, b 0.01 s-1 and 950 °C, c 0.01 s-1 and 1050 °C, d 10 s-1 and 850 °C, e 10 s-1 and 950 °C, f 30 s-1 and 1050 °C

Fig. 8 True stress-strain curves of specimens interruptedly compressed at 900 °C and 1 s-1 at interrupted strains of 0.025, 0.112, 0.3, and 0.6

Fig. 9 a EBSD analysis (showing austenite in blue, δ-ferrite in red, and LABs in white solid lines). b TEM image of the microstructure of the specimen after the compression was interrupted at a strain of 0.025

Fig. 10 EBSD analysis (showing austenite in blue, δ-ferrite in red, LABs in white solid lines, and HABs in black solid lines) and TEM image of the microstructure after the compression was interrupted at strains of a, b 0.112, c, d 0.3

Fig. 11 Dependence of a work-hardening degree, b dynamic softening degree on the deformation temperatures and strain rates

Fig. 12 a EBSD analysis (showing austenite in blue, δ-ferrite in red, and HABs in black solid lines). b TEM image of the microstructure of the specimen after the compression was interrupted at a strain of 0.6