Anisotropy of Extrusion Texture and Adiabatic Shear Sensitivity of TC4 Alloy Bar

Abstract:

The microstructural orientation and texture developed during titanium alloy processing have significant effects on its dynamic mechanical behavior, particularly on adiabatic shear characteristics. In this study, the compression anisotropy and adiabatic shear behavior of the α+β TC4 alloy bar were investigated under high strain rates along the extrusion direction (ED) and transverse direction (TD) using a Split Hopkinson Pressure Bar (SHPB) apparatus. The localized deformation evolution and mechanisms were analyzed through Digital Image Correlation (DIC) and Electron Backscatter Diffraction (EBSD) techniques. The results reveal that the α-hcp phase in the extruded TC4 bar exhibits an axially symmetric cylindrical fiber texture. The yield strength in the TD is significantly higher than that in the ED; however, the TD shows greater adiabatic shear sensitivity and a higher tendency for adiabatic shear band (ASB) formation. EBSD analysis indicates that the specific crystallographic orientations induced by the extrusion texture influence yielding behavior by affecting the Schmid factors of dislocation slip systems, thereby leading to deformation anisotropy. The extrusion texture along the ED aligns most grains favorably for the activation of the basal slip system in the α-hcp phase, which has a lower critical resolved shear stress (CRSS), resulting in a lower dynamic yield strength compared with the TD. Meanwhile, the more homogeneous deformation among grains and the weaker thermal effect along the ED contribute to its lower adiabatic shear sensitivity. These findings provide insights into the influence of microstructural orientation and texture on adiabatic shear behavior in titanium alloys, offering guidance for texture control and design strategies to enhance resistance to adiabatic shear failure.