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 alpha-beta 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 beta phase (V-beta). 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 V-beta induced greater stress in the alpha phase and smaller stress in the beta phase close to the alpha-beta interfaces in the initial stages of deformation because of the elastically softer beta phase with lower V-beta. This resulted in greater strain gradients and greater GND density close to the interfaces in the initial stages of deformation within the single alpha-beta colony when the beta phase plastically does not deform.