The microstructure and properties of Ti6Al4V wires after cold drawing are studied. Metalloscope and transmission electron microscopy reveal that the dislocation gliding is the dominant deformation mechanism in the as-drawn wires. During the cold drawing

the microstructure and properties evolution could be separated into three stages. The initial fast strain hardening is mainly caused by deformation of large grain. In this stage entanglement of dislocations begin to form. The second stage is almost a platform. Partial small grains begin to participate in the deformation

which corresponds to the formation of shear bands. As ε0.60

all grains take part in the deformation and grain refi nement is caused by the changing of low-angle geometrically necessary boundaries (GNBs) into high-angle grain boundaries (HAGBs).