A joint analysis of the results of tensile and impact bending tests was used to study viscoplastic properties of specimens of medium carbon microalloyed steel 38G2F (38Г2Ф) subjected to quenching from 900 °C and tempering at 650 °C followed by cooling in various media. For the stages (periods) on the tensile and impact bending curves, the parameters that determine the embrittlement of metal during a test at room temperature have been established. Based on the revealed correlations between the parameters of static and dynamic tests (true stress Sk and impact toughness KCV, relative narrowing ϕк at the moment of specimen rupture and static toughness a), a new approach is proposed for evaluation of the viscoplastic properties of steels in various structural-phase states.