Orientation effect on mechanical properties of commercially pure titanium at room temperature

The effect of sample orientation on the mechanical properties of commercially pure (CP) titanium plate with a transverse split basal texture was investigated at room temperature (RT) using plane strain compression (PSC). A large variation in flow stress of up to similar to 60 pct was found for samples of different orientations. The major sources of this variation were revealed by measuring area fractions for individual twin modes using electron backscatter diffraction (EBSD) and calculating Schmid factors for all important slip and twinning modes. Importantly, the Schmid factors were calculated for all orientations in Euler space because there are significant variations over all orientations for the PSC stress state, unlike uniaxial compression or tension. The Schmid factor analysis and twin data for the wide variety of orientations tested enabled the conclusion to be drawn reliably that higher flow stresses were primarily due to an unfavourable orientation for prism-< a > slip. A greater proportion of {11 (2) over bar2} to {10 (1) over bar2} twinning was also a major factor in the higher flow stresses. Increased strain hardening was observed in the sample orientation that showed a dramatic texture change to a more difficult orientation for further deformation as a result of dominant {10 (1) over bar2} twinning. This indicated that reorientation hardening was the responsible mechanism.