Abstract
An orientation distribution function based model is used for micromechanical modeling of the titanium-aluminum alloys, Ti-0 wt % Al and Ti-7 wt % Al, which are in demand for many aerospace applications. This probability descriptor based modeling approach is different than crystal plasticity finite element techniques since it computes the averaged material properties using upper bound averaging. A rate-independent single-crystal plasticity model is implemented to compute the effect of macroscopic strain on the polycrystal. An optimization problem is defined for calibrating the basal, prismatic, pyramidal slip system and twin parameters using the available tension and compression experimental data. The crystal plasticity parameters of Ti-7 wt % Al are not studied extensively in literature, and therefore the optimization results for the crystal plasticity model realization produce unique data, which will be beneficial to future studies in the field. The sensitivities of the slip and twin parameters to the design objectives are also investigated to identify the most critical slip system parameters. Using the optimum design parameters, the microstructural textures, during the tension test, are predicted by the crystal plasticity finite element simulations, and compared to the available experimental texture and scanning electron microscope—digital image correlation data.
Highlights
Integrated Computational Materials Engineering (ICME) (Allison et al [1]) models for titanium alloys are essential for understanding the effect of crystal plasticity parameters to micromechanical modeling and engineering outputs
The fundamental goal of this study is to identify the slip system parameters of Ti-Al alloys, Ti-0Al and Ti-7Al, using crystal plasticity modeling with the orientation distribution function (ODF) approach
The scanning electron microscope (SEM)-digital image correlation (DIC) data is available at 13.5% tensile strain, it is compared to the crystal plasticity finite element (CPFE) results in Figure 8 for exx, eyy and exy strain fields respectively
Summary
Integrated Computational Materials Engineering (ICME) (Allison et al [1]) models for titanium alloys are essential for understanding the effect of crystal plasticity parameters to micromechanical modeling and engineering outputs. Fitzner et al [33] performed a detailed experimental study to investigate the effect of Al addition to twinning activity in Ti-Al alloys, and they found that at around 7 at % Al there is a turning point in twinning activity and a further increase in Al reduced the twinning activity because of short range ordering and signs of Ti3 Al formation in case of the highest Al content they observed (13 at %) They discussed the 101̄2 < 1̄011 > tensile twin and concluded that it provides a near 90 degrees rotation of the c-axis from a tensile to a compressive stress condition, and increases the intensity of basal texture during compression loading.
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