Temperature dependent work hardening in Ti–6Al–4V alloy over large temperature and strain rate ranges: Experiments and constitutive modeling

• Temperature dependent work hardening is found in compression tests of Ti–6Al–4V alloy.
• Titanium alloy generates higher ductility with increase of temperature.
• Constitutive models are proposed to modeling the flow stresses.
• JCM and KHLM models can characterize the work hardening effect more accurately.

The plastic deformation behaviors of Ti–6Al–4V alloy over wide ranges of strain rate (from 10−4 to 104 s−1) and temperature (from 20 to 900 °C) are investigated by the quasi-static and dynamic uniaxial compression tests. The microstructure evolution of Ti–6Al–4V alloy at different temperatures is discussed. Material generates higher ductility and formability when temperature is higher than 500 °C, which leads to the decrease of work hardening rate. The true stress–strain responses are modeled with the JC, modified JC, KHL and modified KHL models. In detail, a temperature dependent work hardening function is introduced into the original JC and KHL models. The parameters of the four models for Ti–6Al–4V alloy are calculated by GA optimization method. The average standard deviations between the experimental and calculated flow stresses range from 4% to 13%, which validates the accuracy of the models. In addition, comparison of flow stresses at dynamic (10,000 s−1), the work hardening rates at dynamic (7500 s−1), as well as the quasi-static jump experiments were proposed to further validate the models. The modified JC and modified KHL models could characterize the temperature dependent work hardening effect for Ti–6Al–4V alloy over large strain rate and temperature ranges.

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