Dynamic mechanical properties of near-alpha TA19 titanium alloy and application of calibrated constitutive models in cutting simulation

Abstract

Accurate characterization of flow-stress behavior is essential for modeling the dynamic deformation and machining response of titanium alloys. In this study, the mechanical behavior of near-alpha TA19 titanium alloy was investigated by quasi-static compression tests at strain rates of 0.001-0.01 s-1 and split Hopkinson pressure bar tests at 25-650 °C and 1500-4500 s-1. Strain-rate sensitivity, thermal softening, and adiabatic temperature rise were analyzed, and measured flow stresses were corrected to obtain isothermal stress-strain curves. Power-Law (PL) and Johnson-Cook (JC) constitutive models were calibrated using the same experimental dataset and quantitatively evaluated. TA19 exhibited positive strain-rate sensitivity and pronounced thermal softening. As the strain rate increased from 1500 to 4500 s-1, the average flow stress increased by 112.447-228.009 MPa, depending on temperature, whereas increasing the temperature from 25 to 650 °C reduced it by 205.226-294.361 MPa. Adiabatic heating increased with strain rate at room temperature but was generally suppressed at elevated initial temperatures. Under 16 dynamic conditions, the PL and JC models produced average absolute relative error ranges of 1.20%-7.24% and 1.54%-12.38%, respectively, with overall values of 3.85% and 6.36%. The PL model therefore provided higher overall prediction accuracy, whereas the JC model offered better numerical compatibility for engineering simulation. The calibrated JC model was implemented in AdvantEdge to investigate the effects of feed rate, cutting speed, and rake angle. Increasing feed rate reduced shear strain, plastic strain rate, and normalized cutting loads. Increasing cutting speed markedly increased plastic strain rate and redistributed the load between the cutting- and thrust-force components. A larger rake angle facilitated chip flow and reduced cutting temperature and normalized thrust force. These results clarify the coupled effects of strain hardening, strain-rate strengthening, thermal softening, and tool-chip interaction and provide a basis for constitutive-model selection and cutting-parameter optimization of TA19 titanium alloy.