Microstructural parameters affecting creep induced load shedding in Ti-6242 by a size dependent crystal plasticity FE model

Unified constitutive modelling for two-phase lamellar titanium alloys at hot forming conditions

“…The plastic deformation of two-phase titanium alloys with colony microstructure is activated through two types of slip mode, namely the hard and the soft slip mode [30,31], as illustrated in Figures 1a and 1b, respectively. The soft slip mode corresponds to systems in which dislocations glide parallel to the interface and transmit freely across a/b interfaces due to the presence of common slip system between the two phases [25,30]. The hard slip mode, on the other hand, corresponds to systems in which slip transmission is impeded by a/b interfaces due to the absence of a common slip system between them.…”

“…When h falls in the range 0°-45°or 45°-90°, the slip mode is somewhere between hard and soft slip mode. With the increase of strain, the slip mode turns into soft slip mode gradually, resulting in flow softening [25,30,31].…”

“…In this study, a normalized variable x is adopted to describe the extent of slip mode transition from hard slip mode to soft slip mode in terms of overall response of the material, representing the average behaviours of colonies with different misorientation angles. The transition of slip mode develops with increasing plastic strain and the internal variable x is suggested to be formulated as below [30,31]:…”

“…Schematics of (a) soft and (b) hard slip modes in titanium alloys with lamellar microstructure [30] (l a and l b are the thicknesses of a and b lamellae, respectively).…”

Recent developments in plastic forming technology of titanium alloys

“…It is capable of simulating the complex two-phase titanium alloys and can obtain the deformation inhomogeneity and strain localization of the grains though it is computational demanding. Ghosh et al [105][106][107] estab- [108][109][110][111] presented a CPFE model for Ti-6Al-4V with duplex microstructure. The model accounts for distinct three-dimensional slip geometry for each phase, anisotropic and length scale dependent slip system strengths, the non-planar dislocation core structure of prismatic screw dislocations in the primary  phase, and crystallographic texture.…”