Crystal-plasticity finite-element analysis of anisotropic deformation behavior in a commercially pure titanium Grade 1 sheet

A crystal-plasticity finite-element method was used to study the deformation behavior of a commercially pure titanium Grade 1 sheet upon different strain paths. Prismatic slip, pyramidal slip, basal slip, two types of pyramidal slip, {101¯2} twinning, and {112¯2} twinning were taken into consideration. The material parameters were systematically determined considering the role of each active deformation mode. The simulation results were in good agreement with the experimental results with respect to evolution of the Lankford value, stress-strain curves, contours of plastic work, and texture evolution for the strain paths examined in this study. The mechanism of anisotropic deformation behavior was then investigated, focusing especially on the role of the activity of twinning in the plastic deformation. It was found that the twinning activity significantly affected the following characteristics: the anisotropies in the Lankford value and work hardening under compression and the tension-compression asymmetries in the stress-strain curves in the rolling direction. The detwinning activity also affected stress-strain curves upon reverse loading, in particular in the rolling direction. To systematically understand the deformation mechanism, the effect of slip activity on the deformation behavior is also discussed.