Flow softening during hot working of Ti-6Al-4V with a lamellar colony microstructure

The crystallographic texture changes are determined to explain the flow observations of titanium alloys. Load-stroke data from the compression tests were corrected to account for load train deflection and then converted to true stress-true strain curves assuming uniform constant volume deformation, an approach validated by finite element method simulation of the isothermal, hot compression test performed with the DEFORM computer code. The principal results consist of the constitutive behavior of the Ti-6Al-4V alloy with the colony microstructure in compression versus tension, estimates of flow softening/hardening from polycrystalline plasticity calculations, and selected microstructure observations.