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 (α+β) 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 α 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.