Crack nucleation and growth in α/β titanium alloy with lamellar microstructure under uniaxial tension: 3D X-ray tomography analysis

In situ tensile tests were carried out on notch axisymmetric samples of as-cast (alpha+beta) Ti alloy to analyze evolution of void/micro-crack with the help of X-ray Synchrotron tomography. The results indicate that junctions or boundaries of a colonies could be the most vulnerable sites for voids nucleation. In addition, during the growth and coalescence procedure, ligaments could be observed on the voids/micro-crack. A bypassing & fracture propagating approach was proposed and validated to interpret the existence of ligaments. In the propagating procedure, due to lacking of hard precipitations, microstructure zone and other inserting colony could play a role as hard obstacle in the growing path. This could induce a bypassing & fracture propagating approach for void coalescence and micro-crack growth.