Mechanical Response of Carbon Steels from Quasistatic to Extreme Strain Rates

We investigate the hardness and microstructural evolution of three carbon steels, AISI 1010, 1045, and 1082, over strain rates spanning from quasistatic to extreme regimes ( ~ ∼ 10 8 s −1 ) using a self-consistent approach that combines indentation-based methods. While carbon content increases across compositions, the chemistry of individual microstructural constituents remains essentially unchanged; higher carbon primarily alters the relative fractions of ferrite and pearlite, revealing the effect of the second phases on deformation. Hardness evolves in two regimes: at low strain rates, deformation is dominated by dislocation slip and characterized by a decreasing strain rate sensitivity as pearlite content increases, while at high-to-extreme strain rates, hardness exhibits a pronounced hardness upturn, regardless of the steel grade. A simple rule-of-mixtures composite model, combining ferrite and pearlite responses, captures the extreme rate behavior, which is consistent with the Newtonian nature of dislocation drag-dominated plasticity.