Analysis of shear stress promoting void evolution behavior in an α/β Ti alloy with fully lamellar microstructure

Abstract

With the help of X-ray synchrotron tomography, in situ tensile tests have been performed on Ti-6Al-4V titanium alloy with full lamellar microstructure. The rendered 3D images have shown that void could nucleate as soon as the material yields, although local stress triaxiality (T=0.472) seems not to be high and even tends to maintain a constant value in the following damage steps(T=0.474~0.510). It can be inferred that local stress triaxiality could not be the dominating factor during damage development in this current work.

Analysis of hybrid fracture in α/β titanium alloy with lamellar microstructure

“…Thus, a void could originate at the interface of α/β phases and propagate along this interface. This assumption agrees well with the results of our previous work [8,9].…”

“…It can be observed that the width of α lamella varies 3 μm~5 μm, whereas β lath seems to maintain the width less than 1 μm (see Fig.1(c),(d) ). In the authors' previous studies [8,9], some tensile tests were completed; the results and details can be found in [8,9]. Only post-mortem fracture surface and cross-sectional microstructure observations were additionally performed here.…”

“…According to our previous work, no twinning was found during deformation [8,9]. Only slip systems activated in the α/β phases were considered.…”

“…The heterogeneous deformation behavior of the two phases leads to plastic incompatibilities [2,3] which promote a damage initiation in the form of void nucleation and growth. The α/β interface decohesion [4][5][6][7] occurs especially in alloys with long straight interfaces(full lamellar microstructure) [8,9]. To expand the future use of these alloys, it is necessary to understand well the relation between plastic inhomogeneity and damage initiation.…”

A Unified Constitutive Model of Stress Relaxation of Ti-6Al-4V Alloy with Different Temperatures from Elastic to Plastic Loading

“…The internal stress σ * in the loading stage reflects the strain hardening caused by dislocation interaction [25]. Due to the specific BOR relationship between the lamellae, the colony usually behaves like a grain [26]. The internal stress σ * is described as:…”