Work hardening behavior in polycrystalline α titanium determined by deformation incompatibility

Abstract

In this study, reason for the anisotropy of work hardening behavior in polycrystalline α titanium with transverse direction (TD) split texture was investigated using crystal plasticity finite element (CPFE) analysis. The CPFE analysis successfully reproduced the anisotropy of stress- strain curves even though the effect of dislocation on work hardening was ignored in the condition of analysis. When the relationship between change in work hardening rate and activation of slip systems was investigated using the results obtained by the CPFE analysis, the decrease in work hardening rate was closely related to the activation of primary and secondary slip systems; the activation of primary slip system determined the yield strength and the activation of secondary slip system decreased the work hardening rate due to change in deformation incompatibility between grains. This result shows in the current α titanium that prismatic slip system is the primary slip system and 1^st pyramidal <a> slip system is the secondary slip system, and the activation timings of these slip systems are different depending on tensile direction, resulting in the anisotropic stress-strain relationships.