Crystal Plasticity Analysis of Microscopic Deformation Mechanisms and GN Dislocation Accumulation Depending on Vanadium Content in β Phase of Two-Phase Ti Alloy

Inhomogeneous deformation of a single α-β colony in a Ti–6Al–4V alloy under uniaxial tensile conditions was numerically simulated using a crystal plasticity finite element (CPFE) method, and we predicted density changes in geometrically necessary dislocations (GNDs) depending on the vanadium concentration in the β phase (Vβ). The geometric model for the CPFE analysis was obtained by converting data from electron back-scatter diffraction patterns into data for the geometric model for CPFE analysis, using a data conversion procedure previously developed by the authors. The results of the image-based crystal plasticity analysis indicated that smaller Vβ induced greater stress in the α phase and smaller stress in the β phase close to the α-β interfaces in the initial stages of deformation because of the elastically softer β phase with lower Vβ. This resulted in greater strain gradients and greater GND density close to the interfaces in the initial stages of deformation within the single α-β colony when the β phase plastically does not deform.