In situ EBSD/HR-DIC-based investigation on anisotropy mechanism of a near α titanium plate with strong transverse texture

Abstract

The effect of strong transverse(T) texture on anisotropy deformation mechanism of Ti60 plate was in-situ investigated using the EBSD and the high resolution-digital image correlation (HR-DIC) technique. The yield strength and the ultimate tensile strength is in descending order: TD > RD > 45°, and the ductility shows the opposite trend. The tensile anisotropy related to the discrepancy of activated slip systems in RD, 45°, and TD. In yielding stage, prism<a> slip dominated in RD, basal<a> slip dominated in the 45° direction, while pyram <c+a > slip dominated in TD. The anisotropy coefficient χ was proposed to evaluate the resistance discrepancy based on all the activated slip systems, which well explained the trend of the tensile strength anisotropy. The ductility anisotropy has been analyzed through slip transmission and slip-GB interaction using HR-DIC technology, which is determined by residual dislocation under different tensile directions. The slip transmission can be easily achieved when the Burgers vector of incoming grain is a [2‾ 110] and the Burgers vector of outcoming grain is a [112‾ 0] in 45° direction, which can effectively weaken stress concentration on the grain boundary leading to the greatest ductility among three tensile directions. The dislocation structures in three directions have been analyzed under two-beam condition and weak beam dark field (WBDF) images.