This paper presents the results of statistical tests, carried out to identify the mechanical properties of Ø 16-150 mm VT6 titanium alloy bars, as a function of their post-annealing chemical composition and structure. It is shown that the high variation of mechanical properties may be, due to fluctuations in the grade composition and structure type. 50% to 60% of variations in strength properties are due to composition + structure co-effects. To improve the stability of such properties, the paper identifies maximum permissible total fluctuations in the chemical composition in terms of aluminum/molybdenum equivalents of alloying elements and impurities. The research team has fitted the regression dependencies for evaluating the mean values of the mechanical properties of Ø 16-60 mm VT6 bars, as a function of the structure type and aluminum/molybdenum equivalents of the alloying elements and impurities.

The results of statistical studies of the strength properties of rods made of heat-resistant titanium alloys at test temperatures of 20-600 °C are represented. The initial data for the research were the results of experiments published in various sources from the 1960s to 2019.The chemical composition of the alloys has been compared by aluminum and molybdenum equivalents and tensile strength at various temperatures. With an increase in the degree of alloying with a-stabilizers and neutral hardeners, the heat-resistant properties of alloys increase and remain at higher temperatures. However, this may reduce the thermal stability of alloys with an aluminum equivalent of more than 9.0%. The highest strength properties while maintaining thermal stability have alloys with aluminum equivalents of 8.5-9.0% and molybdenum of 1.0-4.5%. Regression dependences of the average values of strength properties on the test temperature, silicon content, and aluminum and molybdenum equivalents of alloying elements and impurities have been determined.

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The mechanical properties of different classes of titanium alloys have been compared during tensile tests and upset tests in the temperature range of 20-1200 °C. It has been established that at temperatures of 20–500 °C, the maximum strength is observed for the α+β-transition alloys, and at 600–800 °C – for heat-resistant near α-and α+β-alloys. At temperatures exceeding 900 °C and up to the polymorphic transformation point, the softening of titanium alloys is mainly defined by the content of α-stabilizers and neutral hardeners. At temperatures above the polymorphic transformation point, the tensile strength does not depend on the aluminum and molybdenum equivalents.