Constitutive modeling and numerical simulations for dynamic strain aging in MMFX steel at elevated temperatures

Abstract

The mechanical behavior of Martensitic Microcomposite Formable Steel alloy for a wide range of temperatures from room temperature to 923 K and strain rates from 0.0015 s−1 to 500 s−1 is investigated focusing on the effect of dynamic strain aging. A new constitutive model including an additional flow stress component due to the dynamic strain aging induced hardening is proposed for Martensitic Microcomposite Formable Steel alloy, which has not been nonexistent so far. A Weibull distribution probability density type function is introduced to describe this hardening. The dynamic strain aging stress element is defined as a function of temperature, equivalent plastic strain, and its rate since its occurrence and characteristics depend on those factors. To check the validity of the proposed model, experimental data from quasi-static and dynamic loading tests in the literature are utilized. The new finite element code corresponding to the proposed model is also developed and validated using experimental data. Lastly, strain rate sensitivity is discussed to investigate the effect of dynamic strain aging.