Effect of Crystal Lattice Parameters of Surface Gas-Saturated Layers on Ductility of Titanium Alloys Under Tensile Tests

Sheets from titanium alloys VT18U and Ti6Al7Nb are studied after isothermal annealing at 560°C for 1000 h in an air atmosphere. Tensile tests of the specimens are performed. The elongation of the samples of VT18U and Ti6Al7Nb is shown to differ substantially in oxidized condition. Metallographic, fractographic and x-ray diffraction analyses are performed for determining the main parameters affecting the ductility of the alloys in oxidized condition. The effect of the surface gas-saturated layer on the mechanical properties of the alloys is studied, and the factors influencing the ductility of the oxidized samples in tensile tests are determined.