A criterion for slip transfer in Ti-6Al-4V determined using HR-DIC: toward a quantitative assessment of slip length in microtextured regions

The mechanical performance of titanium alloys is of critical importance for component design. Improving predictive capability requires new tools capturing the consequences of microtexture on the development of plastic deformation. In particular, characteristics of grain boundaries determine long-range strain localization, which is detrimental to a variety of properties. In this study, interactions between slip bands and α/α grain boundaries were characterized using high resolution digital image correlation and electron back-scattered diffraction to statistically analyze slip transfer, and determine a predictive criterion. This technique enabled a reliable identification of active slip systems to account for their competitive operation. While basal and prismatic slip are prevalent, < a > type first-order pyramidal slip, or < a > dislocations glide along higher index slip planes, permits to overcome conditions unfavorable for slip transfer. Collected datasets were then used to benchmark indicators reported previously, and determine thresholds leading to the optimum classification performance. A criterion involving m ′ and a Schmid factor-based parameter yielded excellent results. Broad relevance ensues from its insensitivity to the macroscopic strain level. The distributions of effective slip length values were finally computed in microstructures with different degrees of microtexture to illustrate future applications in microtexture-sensitive predictions of mechanical properties of titanium alloys.