The Influence of Severe Plastic Deformation and Subsequent Annealing on Structure and Mechanical Properties of VT35 Titanium Alloy

The effect of severe plastic deformation by multiple pressing and subsequent annealing on the structure and mechanical properties of VT35 titanium alloy is studied. It is shown that the formation of ultrafine-grained state results in a 40–60% increase of its room-temperature mechanical properties compared to the initial coarse-grained state. A subsequent annealing of the ultrafine-grained VT35 alloy at 773 K improves homogeneity of the structure formed by multiple pressing; the average size of the grain-subgrain structure elements does not increase and there is no precipitation of additional fine α-phase particles in the bulk of β-grains. These structural changes are expected to improve room-temperature mechanical properties of the alloy after its annealing at 773 K. A further increase in the annealing temperature to 873 K is followed by recrystallization, an increase in the average size of the grain-subgrain structure elements and, as a consequence, a degradation of the mechanical properties. It is found out that an increase in the total imposed strain degree within the temperature range of 773–823 K during multiple pressing of VT35 alloy provides an additional 65–70% improvement of its room-temperature properties compared to the initial coarse-grained state.