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The oxidation effect at air aging on mechanical properties and fracture of β titanium alloy Ti-15V-3Cr-3Al-3Sn-1Mo-1Zr produced by combined rolling has been studied. It was shown that aging in ambient air at 450 °C for 5 hours leads to the formation of an oxide layer of 1.5-2 µm thick with a decrease in the strength and ductility under tension at room temperature. The study of the lateral and fracture surfaces revealed that the reason for the decrease in ductility of alloy samples with the oxide layer in tension is the development of surface microcracks which density and depth increases with strain. The spread of the microcracks into a depth exceeding the thickness of the oxide layer leads to the development of brittle-viscous fracture. The decrease in strength properties can be associated with corresponding decrease of effective cross section of oxidized samples by formation of brittle subsurface layer up to 40 µm in thickness. [ABSTRACT FROM AUTHOR]

Studies of the effect of radial-shear rolling and subsequent aging on the structure, mechanical properties and creep of VT22 titanium alloy have been carried out. It is shown that the modification of the structure by radial-shear rolling in the temperature range 1123–1023 K and subsequent aging at a temperature of 773 K makes it possible to increase the strength properties of the VT22 alloy under tension in the temperature range 293–773 K by 40–30% compared to the initial state. Under creep conditions an increase in the creep resistance of the modified structure is observed at stresses below 0.5 of the yield stress. [ABSTRACT FROM AUTHOR]

In this paper, we study the effect of the hydrogen presence in a solid solution on the stability of the structural and phase state and the mechanical properties of the ultrafine-grained titanium alloy of the Ti-Al-V-Mo system (VT16 grade) in the temperature range of 573–973 K in a vacuum and air. It was established that during annealing under conditions of hydrogen degassing from the ultrafine-grained structure, a β → α″ → α phase transformation and redistribution of alloying elements are observed, which contribute to the formation of a thin-plate (α + α″ + β) structure in β grains and an increase in the mechanical properties of the alloy. [ABSTRACT FROM AUTHOR]

Hydrogen effect on the deformation behaviour of the ultrafine-grained titanium alloy (VT16 grade) is studied at the temperature interval (293–973) K. Hydrogenation to the concentration of 0.3 wt % is found to lead to an increase in the values of uniform deformation and total deformation to failure at temperatures 293–573 K. In the range of higher temperatures (673–973) K, hydrogen presence reduces the resistance of the ultrafine-grained VT16 alloy to the localization of deformation at the macro-level and value of deformation to failure. Possible reasons for the increase in the transition temperature of the ultrafine-grained VT16 alloy to the superplastic state and the decrease in the temperature interval of the manifestation of its superplastic properties in the presence of hydrogen in a solid solution are discussed. [ABSTRACT FROM AUTHOR]

Effect of preliminary hydrogenation on formation of the ultrafine-grained structure in titanium alloy of Ti-Al- V-Mo system (VT16 grade) under severe plastic deformation was examined by the methods of transmission electron microscopy and X-ray diffraction analysis. Hydrogenation to 0.15 wt. % is found to decrease the value of plastic deformation (by ~2 times) and treatment temperature (from 1023 to 923 K) during formation of the ultrafine-grained hierarchically organized internal structure in the VT16 alloy. Formation of the hierarchically organized internal structure in the VT16 alloy is shown to lead to an increase in yield strength, ultimate strength, and resistance to hydrogen embrittlement at room temperature as compared to the coarse-grained state. [ABSTRACT FROM AUTHOR]

In this work we investigate the deformation behavior of hydrogenated ultrafine-grained Ti-6Al-4V alloy under creep in the temperature range 723-873 K. The hydrogen presence in the amount of 0.26 wt % in a solid solution is found to lead to a decrease in the rate of steady-state creep and strain to failure and increase in time to failure of Ti-6Al-4V alloy. Possible reasons of a rise in the creep rate and strain to failure of the alloy under creep and simultaneous hydrogen degassing are discussed. [ABSTRACT FROM AUTHOR]

Effect of annealing at temperature below recrystallization temperature on creep of the ultrafine-grained (α + β) titanium VT16 alloy at temperature of 723 K and rate interval of 10-6-10-5 s-1 is studied. Preliminary annealing of the ultrafine-grained VT16 alloy at temperature of 673 K for 6-30 hours is found to result in decrease of steady-state creep rate and increase in deformation value and time to failure. Possible reasons of increase in creep resistance of VT16 alloy after prerecrystallization annealing are discussed. [ABSTRACT FROM AUTHOR]