Relationship among microstructure, mechanical properties and texture of TA32 titanium alloy sheets during hot tensile deformation

Abstract

The relationship among microstructure, mechanical properties and texture of TA32 titanium alloy sheets during hot tensile deformation at 800 °C was investigated. In the test, the original sheet exhibited relatively low flow stress and sound plasticity, and increasing the heat treatment temperature resulted in an increased ultimate tensile strength (UTS) and a decreased elongation (EL). The deformation mechanism of TA32 alloy was dominated by high angle grain boundaries sliding and coordinated by dislocation motion. The coarsening of grains and the annihilation of dislocations in heat-treated specimens weakened the deformation ability of material, which led to the increase in flow stress. Based on the high-temperature creep equation, the quantitative relationship between microstructure and flow stress was established. The grain size exponent and α phase strength constant of TA32 alloy were calculated to be 1.57 and 549.58 MPa, respectively. The flow stress was accurately predicted by combining with the corresponding phase volume fraction and grain size. Besides, the deformation behavior of TA32 alloy was also dependent on the orientation of predominant α phase, and the main slip mode was the activation of prismatic 〈a〉 slip system. The decrease of near prism-oriented texture in heat-treated specimens resulted in the enhancement of strength of the material.