Study on the constitutive model of porous titanium alloy

Abstract

Porous titanium (Ti) alloys usually need high-speed precision machining before they are put into practical applications. Therefore, it is necessary to study the materials’ mechanical properties under conditions of larger strain rate and higher temperature in order to understand the processing mechanism and determine the appropriate processing parameters. In this study, the mechanical properties of porous titanium alloys of two porosities were first investigated by quasi-static compression tests and split Hopkinson pressure bar tests under different conditions. Then, the constitutive models of the flow stress were fitted. From the results of quasi-static compression tests, it was found that the static mechanical properties of porous titanium alloys decreased rapidly with increase in porosity. From the result of the split Hopkinson pressure bar tests, the strain rate sensitivity and temperature sensitivity of porous titanium alloys were determined. The mechanical properties of porous titanium alloys increased with strain rate increase in the range 1000–3000 s−1. The alloys exhibited a temperature-softening effect at 100°C, while they had a temperature-hardening effect at 300°C. The constitutive model could describe the strain-hardening rate of the material appropriately, but the accuracy of the simulated results needed to be improved compared with experimental values.