Tensile deformation of texture-controlled titanium with high oxygen content at room temperature

Abstract

Alloys of titanium and oxygen have demonstrated increased tensile strength, and they show promise for a range of applications. However, the microstructure and the mechanisms of high-oxygen titanium alloy deformation remain uncertain. To address this gap in knowledge, we investigated the tensile properties and deformation mechanisms of texture-controlled Ti–O alloys with high oxygen contents. We created Ti–O alloys with oxygen contents of 0.058%, 0.21%, 0.41%, 0.65%, and 0.71% by mass. These alloys possessed f0001gh1010i texture, and they were deformed along the rolling direction. We found that oxygen content was correlated with increases in 0.2% proof stresses and tensile strengths, which conformed to the solid-solution strengthening law. All specimens exhibited total elongation of higher than 20%. Twin deformation had minimal effect on strength and elongation, and the major deformation mode was for slip deformation. The uniform elongation and gradient of the work hardening rate increased at oxygen contents above 0.61 mass%. As oxygen content increased, double slipping occurred in more grains. That is because pyramidal <a> slip is activated, and its operation induces the crystal orientation to the stable orientation under tensile deformation. Double slipping easily occurs in a grain with stable orientation. Therefore, dislocations were frequently cut and tangled with each other. As a result, the gradient of the work hardening rate increased, and uniform and total elongation increased in Ti–O alloys with abundant oxygen. These findings are useful to extend oxygen utilization as an alloying element in Ti.