Damage evolution and failure in a titanium alloy: Revealed by 3D in situ X-ray tomography

In this work, damage/fracture development of Ti-6Al-4V alloy was analyzed with the help of in situ tensile test by synchrotron X-ray tomography. The result shows that during the whole damage/fracture procedure for Ti-6Al-4V alloy, the value of stress triaxiality (T) seems to maintain as a constant (T = 0.472–0.510) and to be adjacent with the critical value (Tc=0.49). This can result in the fracture of the alloy in the way of Mix mode (component induced by cleavage component and ductile component). With the help of X-CT scanning, voids evolution were clearly realized and characterized during damage development. On the basis of void tracking results, Rice-Tracey damage model and Huang damage model were adapted to depict and predict the voids growing behavior by calibrating the material parameter. Finally, the micro-mechanism of the mix damage mode was revealed, which can be attributed to local internal shear stress. The significant act of microstructure morphology on the component from mix damage mode was also determined and discussed.