Fig. 1 Microstructures of 254SMO: a as-received state, b after soaking at 1,200 °C for 180 s, and subsequent water quenching

Fig. 2 True stress–true strain curves for 254SMO at different strain rates with the temperatures of 1,000 °C a, 1,050 °C b, 1,100 °C c, 1,150 °C d

Fig. 3 Plots of \( \ln (\dot{\varepsilon }) \) versus ln[sinh(ασp)] a and ln[sinh(ασp)] versus (10,000/T) b

Fig. 4 Variation of the Zener–Hollomon parameter with flow stress

Fig. 5 Power dissipation maps for 254SMO at true strains of 0.2 a, 0.4 b, 0.6 c, 0.8 d, 1.0 (e), 1.1 f (The contour number represents the percentage efficiency of power dissipation)

Fig. 6 Optical micrographs of 254SMO deformed to a true strain of 1.2 at the strain rate of 0.01 s-1 and the temperatures of 1,000 °C a and 1,050 °C b

Fig. 7 a SEM micrograph of 254SMO deformed to a true strain of 1.2 at the strain rate of 0.01 s-1 and temperature of 1,050 °C, b EDS analysis of chemical composition of precipitates in Fig. 7a

Fig. 8 a TEM micrograph of precipitates in the specimen deformed to a true strain of 1.2 at the strain rate of 0.01 s-1 and temperature of 1,050 °C, b selected area diffraction pattern of precipitate in Fig. 8a

Fig. 9 Phase diagrams of 254SMO simulated by themo-calc

Fig. 10 Optical micrographs of 254SMO deformed to a true strain of 1.2 at 1,150 °C and 0.1 s-1a, 1,150 °C and 1 s-1b, 1,200 °C and 0.1 s-1c, 1,200 °C 1 s-1d

Fig. 11 Instability map for 254SMO at the true strain of 1.1

Fig. 12 Optical micrographs of 254SMO deformed to a true strain of 1.2 at 950 °C and 1 s-1a, 950 °C and 10 s-1b, 1,000 °C and 10 s-1c, and 1,050 °C 10 s-1d (The compression direction is vertical)