Substructure evolution of Ti-6Al-2Zr-1Mo-1V alloy isothermally hot compressed in α+β two-phase region

Abstract

Substructure evolution significantly influences the flow behavior of titanium alloys in isothermal hot compression. This paper presents a physical experiment (isothermal hot compression and electron backscatter diffraction, EBSD) and a cellular automaton (CA) method to investigate the substructure evolution of a near-α titanium alloy Ti-6Al-2Zr-1Mo-1V (TA15) isothermally compressed in the α + β two-phase region. In the CA model, the subgrain growth, the transformation of low angle boundaries (LABs) to high angle boundaries (HABs) and the dislocation density evolution were considered. The dislocation density accumulating around the subgrain boundaries provided a driving force and made the transformation of the LABs to HABs. The CA model was employed to predict the substructure evolution, dislocation density evolution and flow stress. In addition, the effects of strain, strain rate and temperature on the relative frequency of the HABs were analyzed and discussed. To verify the CA model, the predicted results including the relative frequency of the HABs and the flow stress were compared with the experimental values.