The effect of temperature on the high-strain-rate response of Co-Al-W- base alloys: Experiments and modeling

Abstract

Two novels Powder Metallurgy (PM) cobalt-based superalloys with a γ/γ’ dual-phase microstructure have been subjected to dynamic uniaxial compression tests at temperatures from 25 °C to 850 °C, and a high strain rate of 2500 s−1, to investigate the effect of temperature on their high-strain-rate response. Compression tests have been performed using a Split Hopkinson Pressure Bar (SHPB), focusing on the temperature-dependent anomalies of the flow stress at high temperatures for both alloys. The analysis of the experimental results indicates an important strain-rate sensitivity and thermal softening effect with a noticeable positive stress peak at high temperatures. Finally, a Johnson-Cook-type constitutive model is developed to describe the flow stress as a function of the temperature, including the anomalous positive peak temperature. The modified JC model presents a good correlation to predict the behavior of both Co-based superalloys over wide ranges of temperatures through simulating the experimental camping with Abaqus. This model offers a potential instrument to simulate and optimize high impact events applications.