Russia researches to improve the durability of aviation Ti-6Al-4V titanium alloys

Two-phase titanium alloys are widely used in aerospace and engine manufacturing due to their high specific strength and corrosion resistance, but improving their durability is a pressing task in the development and production of gas turbines engine components, such as compressor blades and disks, will bear a large tensile load during operation.

At present, two-phase submicrocrystalline titanium alloys have been widely used in the world to manufacture gas turbine engine components operating under high cyclic loads and high-temperature environments of 201-351 °C. But so far, the fatigue strength of titanium alloys in this working temperature range has not been studied. Scientists from the Faculty of Mechanics and Technology of the Perm University of Technology studied the properties of the Ti-6Al-4V alloy composed of aluminum, vanadium, and titanium and evaluated the alloy’s performance at a maximum temperature of 351°C.

According to the researchers, the test was carried out using hot-rolled Ti-6Al-4V alloy bars with a diameter of 20 mm, which underwent standard heat treatment: hardening at 966 °C and annealing at 676 °C for 4 hours; At the temperature of 651°C, the rods were processed by four equal-diameter angular extrusions; finally, the mechanical tensile tests were carried out at room temperature and 351°C.

All samples used for fatigue testing were made by turning and mechanical polishing and the microstructure of the material was analyzed in longitudinal sections of the rod using transmission electron microscopy.

Compared with the coarse-grained alloy, the Ti-6Al-4V ultrafine-grained alloy obtained by equal angular extrusion exhibited higher tensile strength and higher strength at the working temperature of 351 °C. The research was carried out within the framework of the Academic Strategic Leadership Programme “Initiatives-2030” in accordance with the national mandate. In 2021, Perm University of Technology received a grant of 100 million rubles from the “Initiative-2030” program. “Initial-2030” is the largest program in Russian history to support and develop higher education institutions.