Effect of Hot Deformation under Complex Loading on the Transformation of Lamellar Type Microstructure in Ti-6.5Al-3.5Mo-1.6Zr-0.27Si Alloy

Abstract

The transformation of the lamellar type microstructure to an equiaxed one in two-phase titanium alloys is determined not only by temperature-strain rate regimes but also by the modes of loading. The experimental results of investigations relating to the influence of one- and two-component monotonous loading on microstructure and mechanical behavior of the two-phase Ti-6.5Al-3.5Mo-1.6Zr-0.27Si titanium alloy are presented in this work. It is shown that under conditions of proportional torsion + tension loading the transformation of the lamellar microstructure occurs more uniformly in the transverse section of a sample and over its length than under conditions of simple torsion or uniaxial tension. The transformation is accompanied by formation of a typical texture based on the strain state. The following uniaxial tension in optimal temperature-strain rate regimes of superplasticity is characterized by a lower value of flow stress, uniform distribution of deformation and further microstructure transformation within the whole sample volume.