Dynamic constitutive modeling and adiabatic shear behavior of Ti-6Al-4V alloy under low-temperature impact loading

Abstract

The development of mechanical relationship models and analysis of deformation behaviors under dynamic impact are vitally important for the guidance of part design and cutting processes. Based on cryogenic impact mechanical performance testing, this article introduces an innovative approach to develop a cryogenic constitutive model that describes the material's stress-strain relationship under low temperatures and high strain rates. Initially, the stress-strain curves of materials across a wide temperature range (−196 °C to 600 °C) and high strain rates (4000 s⁻¹ to 10,000 s⁻¹) were acquired via cryogenic static/dynamic compression experiments, along with an analysis of the microstructural evolution patterns. Subsequently, a Johnson-Cook constitutive model incorporating low-temperature considerations was developed, with its reliability verified through analytical computations. Finally, the derived constitutive model and micro-mechanisms were integrated into cryogenic cutting, further substantiating the reliability of the findings. The findings indicate that titanium alloys exhibit significant sensitivity to temperature and strain rate changes; reductions in temperature or increases in strain rate not only augment the material's yield strength but also modify the deformation behavior associated with adiabatic shearing. In comparison to conventional models, the constitutive relationship introduced in this study not only captures the dynamic mechanical properties of materials in the cryogenic phase but also maintains a reliable accuracy, with theoretical errors within 7 %. Moreover, the model's practicality and the guidance provided by micro-mechanisms were validated through an amalgamation of cryogenic cutting experiments and simulations.