Fig. 1 Schematics showing the hot deformation experiments with different parameters

Fig. 2 Stress-strain curves of samples deformed at different temperatures with different strain rates

Fig. 3 EBSD images of prior austenite grain boundary of samples at: a T = 800 ℃, without deformation, c T = 800 ℃, $\dot{\varepsilon }$ = 0.01 s−1, e T = 800 ℃, $\dot{\varepsilon }$ = 1 s−1; b T = 1000 ℃, without deformation, d T = 1000 ℃, $\dot{\varepsilon }$ = 0.01 s−1, f T = 1000 ℃, $\dot{\varepsilon }$ = 1 s−1

Fig. 4 Prior austenite grain size of samples with different hot deformation in the first series of experiments

Fig. 5 Prior austenite grain size in the hot deformed samples in the second series of experiments

Fig. 6 Grain boundary observed by EBSD and SEM morphology corresponding to grain boundary image of samples at 800 ℃ with different strain rates a, b without deformation, c, d 0.01 s−1, e, f 1 s−1, a, c, e EBSD images, b, d, f SEM images

Fig. 7 Grain boundary observed by EBSD and SEM morphology corresponding to grain boundary image of samples at 1000 ℃ with different strain rates a, b without deformation, c, d 0.01 s−1, e, f 1 s−1, a, c, e EBSD images, b, d, f SEM images

Fig. 8 Statistical data of ferrite grain size a and pearlite colony size b in the samples in first series of experiments

Fig. 9 Statistical data of ferrite grain size a and pearlite colony size b in the samples in second series of experiments

Fig. 10 Lamellar spacing of pearlite in the samples in first series of experiments

Fig. 11 Microhardness of the samples in first series of experiments

Fig. 12 Lamellar spacing of pearlite in the samples in second series of experiments

Fig. 13 Ratio of ferrite grain size to pearlite colony size in different samples

Fig. 14 Relationship between ferrite grains and pearlite colonies of a, d P1, b, e P2, c, f P3 samples