Comparison of slip system activation in Ti-6Al-2Sn-4Zr-2Mo and Ti-6Al-2Sn-4Zr-6Mo under tensile, fatigue and dwell-fatigue loadings

Abstract

The deformation systems operating in Ti-6Al-2Sn-4Zr-2Mo and Ti-6Al-2Sn-4Zr-6Mo at the onset of plastic slip were characterized by means of monotonic in-situ tensile tests performed in a scanning electron microscope. A slip traces analysis was carried out using the local crystalline orientation characterized by the electron backscattered diffraction technique. The activation of the involved deformation processes were then characterized step by step and the critical resolved shear stress was estimated. Interrupted fatigue and dwell fatigue tests were conducted on both alloys as well to study the possible specificities associated to the operating slip system distribution under cyclic loadings. The main challenge of this work is thus to detect any significant difference in deformation behavior between both alloys that could explain, even partly, the difference they exhibit in dwell fatigue regime. A potential relationship between the operating slip systems and dwell-fatigue life debit is finally discussed.