Features of the turbocharger’s rotor vibration in unstable region

In this paper the effect of intensive plastic deformation on damping properties of titanium Ti2 is investigated. Cast samples, screw extruded samples and annealed samples were tested at room temperature. The cast titanium shows the high damping. Annealed samples leads to a dramatic reduction in energy dissipation (2.4 times). Screw extruded titanium with submicrocrystalline structure have smaller logarithmic decrement compared to the cast titanium, but higher compared to the annealed samples (1.73 times higher than annealed). ?-titanium workpieces in an equilibrium state after annealing are widely used for large scale production of real parts. Therefore, because the intensive plastic deformation positively effects on Ti2 titanium damping properties compared with the annealed condition, that its use for production of the parts working in variable load conditions will increase their life time. Additional thermal treatment of deformed samples slightly increases the logarithmic decrement due to the reduction of internal stresses and the number of defects.