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The H13-mod steel optimized by composition and heat treatment has reached the performance index of the shield machine hob. The hot deformation behavior of the H13-mod steel was investigated by compression tests in the temperature range from 900 to 1150 • C and the strain rate range from 0.01 to 10 s −1 . The true stress-strain curve showed that the rising stress at the beginning of deformation was mainly caused by work hardening. After the peak stress was attained, the curve drop and the flow softening phenomenon became more obvious at low strain rates. The flow behavior of the H13-mod steel was predicted by a strain-compensated Arrhenius-type constitutive equation. The relationship between the material constant in the Arrhenius-type constitutive equation and the true strain was established by a sixth-order polynomial. The correlation coefficient between the experimental value and the predicted value reached 0.987, which indicated that the constitutive equation can accurately estimate the flow stress during the deformation process. A good linear correlation was achieved between the peak stress (strain), critical stress (strain) and the Zener-Hollomon parameters. The processing maps of the H13-mod steel under different strains were established. The instability region was mainly concentrated in the high-strain-rate region; however, the microstructure did not show any evidence of instability at high temperatures and high strain rates. Combined with the microstructure and electron backscattered diffraction (EBSD) test results under different deformations, the optimum hot working parameters were concluded to be 998-1026 • C and 0.01-0.02 s −1 and 1140-1150 • C and 0.01-0.057 s −1 . mechanical properties of H13 steel by optimizing the composition and heat-treatment conditions and applying surface treatments [7][8][9][10][11][12][13]. However, the H13 steel prepared by these processes does not demonstrate a good match between strength and toughness and cannot be used under complex geological conditions. Therefore, the development of a hob material with both strength and toughness is important.An increase in the carbon content of steel is well known to increase its strength and decrease its plastic toughness. However, an excessively high carbon content causes an increase in the brittleness of the steel. Therefore, we strictly controlled the carbon content in the range from 0.48% to 0.52%, optimized the content of other major alloying elements, reduced the impurity content and controlled the shape and size of inclusions to improve the performance of steel. The modified H13 steel, hereafter referred to as H13-mod, was developed by optimizing the heat-treatment conditions. Its hardness reaches 57 HRC and its impact toughness is 15 J/cm 2 , which fully satisfies the performance requirements of the shield hob.H13-mod exhibits excellent mechanical properties. However, whether it can be processed into a qualified part product is not only determined by the material's characteristics but also by the processing technology. At the ...

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