The mechanisms for strengthening under dynamic loading for low carbon and microalloyed steel

•Examination of the mechanical response of 4 steel grades with Taylor impact experiments.•Identification of effects of microstructure on dynamic behavior of studied steels.•Inhomogeneity of mechanical state of Taylor specimen studied through hardness maps.•Discussion of mechanisms of different strengthening modes under dynamic loading.•Source of flow curves of the studied materials for a wide range of strain rates. Taylor impact experiments were conducted to examine the mechanical behavior of four grades of structural steels. The dynamic mechanical response of microalloyed (HSLA), bainitic (MnB), low carbon (LC) and interstitial free (IF) steels at high strain rate loading were investigated systemically through Taylor impact test, over the range of impact velocities: 220 m/s, 270 m/s and 300 m/s. The study was focused on understanding the effect of microstructure on dynamic behavior of investigated materials. The various metallurgical phenomena that influence the mechanical behavior of the investigated steels during Taylor testing are difficult to isolate experimentally. In the present study, the data needed to interpret mechanical tests performed to define the inhomogeneous mechanical state of the steel specimens were obtained from the results of the hardness distributions and microstructural analysis. Examination of the cross sections of the tested specimens reveals that the work hardening, represented by hardness distributions, expands non-uniformly along the length and width of the Taylor specimen. This distribution appears to be related to the chemical composition and microstructure of the investigated steels. The mechanisms of different strengthening modes were discussed based on previous analysis of the uni-axial stress and strains response of these materials.