Dynamic Mechanical Behavior and Constitutive Models of S890 High-Strength Steel at Intermediate and High Strain Rates

High-strength steel is an effective choice to satisfy the demands of advanced manufacturing engineering and construction engineering. The complex and severe working environments for high-strength steel require the designer to take the dynamic mechanical properties into consideration. Thus, the main subjects of this paper are the dynamic strain–stress relationship and the strain rate-strengthening effect of S890 high-strength steel. Experimental studies with a wide range of strain rates were conducted using a dynamic tensile testing system (for intermediate strain rate) and a Split Hopkinson Pressure Bar testing system (for high strain rate). The strain rate effect of S890 steel was quantitatively investigated. The global dynamic increase factor (DIFavg) values were tested to be 1.132 at a strain rate of 200 s−1 and 1.214 at 5292.8 s−1, which indicates that S890 high-strength steel was less sensitive to strain rates than mild steel and other structural steels with lower strength. Based on the Johnson–Cook (J–C) model and the Cowper–Symonds (C–S) model, strain rate models for the S890 steel are presented for describing the dynamic stress–strain relationship. The C–S model has better accuracy owing to the nonlinear characteristic of the DIFavg of S890 steel.