Global and local strain rate sensitivity of commercially pure titanium

We have performed macroscopic tensile and nanoindentation tests to investigate the effect of oxygen content on the global and local strain rate sensitivity of grades 1, 2 and 4 commercially pure titanium (CP–Ti). Electron backscatter diffraction (EBSD) was used to characterise the crystallographic texture of target samples and orientation of target grains. Slip activities were anticipated by Schmid factor analysis, indicating the relative incidence of type prismatic and basal slips in the macroscopic region, and similarity of potential local deformation between comparative grain orientations. Further slip trace analysis around the residual impressions showed similar slip activity in equivalent orientations regardless of oxygen content. Global and local strain rate sensitivity were evaluated with respect to the influence of texture and grain orientations, respectively. Significant oxygen-dependent rate sensitivity is observed such that the rate sensitivity is inverse to the oxygen content and this effect is agreed on at both macro- and microscopic levels. These findings are potentially important for understanding the influence of oxygen content on the dwell fatigue of Ti alloys and correlating the intrinsic mechanism at the microscopic level to the macroscopic deformation behaviours. [Display omitted] •Macroscopic tensile CSR and nanoindentation jump test were performed on CP-Ti.•Global texture and target grain orientation was characterised by EBSD measurement.•Slip activities on textures and grain orientations were anticipated by Schmid law.•Texture and grain orientation dependent rate sensitivity are observed in CP-Ti.•Rate sensitivity was decreased with an increase of oxygen solutes in multi-scale.