Quasi-static and dynamic investigation of an advanced high strength and corrosion resistant 10 % Cr nanocomposite martensitic steel

Abstract

The mechanical response of an advanced high strength and corrosion resistant 10 % Cr nanocomposite steel (ASTM A1035CS Grade 120) is measured under uniaxial tension and compression at the strain rates of 10−4 s−1, 10-2 s-1, 100 s−1, 700 s−1, and 3000 s−1. The experiments are performed at 22 °C as well as 80 °C to investigate the material behavior at the expected temperature rise due to adiabatic deformation at 15 % strain. Additionally, different compression-shear hat-shaped specimens are tested at quasi-static and dynamic strain rates to investigate the localization behavior of this material. The material exhibits small strain rate sensitivity (SRS) during quasi-static loading, but a pronounced SRS between quasi-static and dynamic strain rates. Tension-compression asymmetry is also observed at both temperatures. Experiments at 80 °C reveal a decrease in flow stress in both tension and compression indicating the material is sensitive to thermal softening due to adiabatic heating. Load-Unload-Reload (LUR) and strain rate jump experiments are performed to investigate the reasoning behind the approximate rate insensitivity of ASTM A1035CS steel during quasi-static strain rates. A new constitutive model is also developed using a novel rate dependent material model with a modified Hockett-Sherby (MHS) hardening model and incorporating Lode angle dependence to capture the tension-compression asymmetry. The model is also used to predict the LUR and strain rate jump experiments. Finally, reasoning behind the unique rate dependent thermo-mechanical behavior of ASTM A1035CS steel is discussed in regards to adiabatic heating, strain-partitioning, and phase transformation.