Effect of the Content of Impurities on the Temperature of Polymorphic Transformation and Properties of High-Strength Titanium Alloys

Abstract

We study the effect of the content of oxygen (carbon) impurities on the temperature of complete polymorphic α + β→β transformation (T_pt) and a set of properties of Ti – 10% V – 2% Fe – 3% Al and VST5553 (Ti – 5% Al – 5% V – 5% Mo – 3% Cr) titanium alloys in the thermally hardened state. We determine the microstructure of the alloys by metallographic analysis and test them for tension and fracture toughness. The dependence of T_pt on the content of impurities in the analyzed alloys is determined. It is shown that the value of T_pt can be found by the method of differential scanning calorimetry whose accuracy is comparable with the accuracy of the method of test quenching. The dependences of the strength and ductile properties of the alloys in tension on the aging temperature are constructed. We also establish the relationship between the fracture toughness of the alloys and the morphology of the primary α-phase.