Abstract
In this paper, the accurate description of the relationship between flow stress and strain of porous titanium alloys at various strain rates and temperatures were investigated with dynamic and quasistatic uniaxial compression tests for a further study on the processing mechanism of porous titanium material. Changes in their plastic flows were described through the one-dimensional Drucker-Prager (DP) constitutive model. Porous titanium alloys were micromilled in a DP simulation. After all parameters had been obtained in the DP model, the experimental and simulated true stress-strain curves and flow stress levels of two porous titanium alloys were compared to estimate the precision of the model. The findings were as follows. First, porous titanium alloys show deformation patterns characterized by pore collapse-induced deformation and have strong stress-hardening effects, but the patterns did not include noticeable plastic-flow plateaus. Second, porosity strongly affects the mechanical strength, strain-rate sensitivity, and temperature sensitivity of both alloys. Third, the DP model sufficiently describes the mechanical properties of both alloys at 25–300 °C and at strain rates of 1000–3000 s−1, with a deviation of 10% or lower.
Highlights
Titanium alloys are increasingly used as structural material for aerospace, shipbuilding, petrochemical, power generation equipment, automotive industries and other fields because of their attractive properties such as high specific strength and high structural stiffness with excellent heat and corrosion resistance [1,2,3,4]
The stress and strain values that correspond with the interface correspond with the interface between the plastic and densification stages are termed as the between the plastic and densification stages are termed as the densification stress and densification densification stress and densification strain, respectively
A a good agreement has been obtained which shows the applicability of the DP constitutive model in good agreement has been obtained which shows the applicability of the DP constitutive model in describing the relationship between flow stress and strain of porous titanium alloys at various strain
Summary
Titanium alloys are increasingly used as structural material for aerospace, shipbuilding, petrochemical, power generation equipment, automotive industries and other fields because of their attractive properties such as high specific strength and high structural stiffness with excellent heat and corrosion resistance [1,2,3,4]. In order to further study the machining mechanism of porous titanium material, it is very important to obtain the accurate description of the relationship between the flow stress and strain of the material under high temperature and high strain rate. Considering that the JC constitutive model is more suitable for the material with significant deformation, high strain rate and high temperature machining, but the description of the dynamic mechanical properties of porous titanium alloy material is limited [28]. It cannot describe the effect of temperature-strengthening. The parameters of the constitutive equation were determined by analyzing the experimental data and micro-cutting simulation of DP constitutive model was carried out to compare with the experimental results in order to verify the rationality of the model
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