Effect of Microtexture on the Stress Corrosion Property of Ti-6Al-3Nb-2Zr-1Mo Alloy

The influence of microtexture on the stress corrosion cracking susceptibility and crack propagation path of a near alpha titanium alloy Ti-6 Al-3 Nb-2 Zr-1 Mo were investigated by the observation of the fracture surfaces and the crack propagating paths using EBSD method. The results showed that the morphologies of the microtexture zones were irregular thin lamellae which were nearly parallel to the rolling plane, with their longitudinal direction extending along the rolling direction, and that the grain orientation in the microtexture zones was their c-axis almost parallel to the transverse direction of the bulk plate. When the loading direction was almost parallel to the longitudinal directions of the microtexture zones, prismatic slip was easily activated in the grains of these zones, so as to decrease the stress concentration at crack tip as well as the stress corrosion cracking susceptibility. When the loading direction was almost perpendicular to the longitudinal directions of microtexture zones, prismatic slip and basal slip were hard to activate and that would lead to localized stress concentration and the formation of micro-cracks, raising the stress corrosion cracking susceptibility of the plate.