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Vladlen Nazarov et al. / Procedia Structural Integrity 40 (2022) 325–333 Vladlen Nazarov / Structural Integrity Procedia 00 (2022) 0 0 – 00

Fig. 7. Tubular specimens Nazarov (2017) (inner diameter is 14 mm, outer diameter is 16.1 mm and working length is 130 mm) made of titanium alloy VT1−0 (English equivalent is Grade−2) after creep tests at 550 o C.

5. Conclusion Experimental data obtained for titanium alloys VT1 – 0, VT5 and VT6 showed that these alloys have large strains significantly greater than 7%. Thus, for the VT1 – 0 alloy at 20 o C, the logarithmic elongation strain at the rupture time is 33%, for the VT5 alloy at 650 o C, the average creep strain is 13%, for the VT6 alloy at 650 o C, the average creep strain is 29%. At the same time, it is shown that the introduction of hydrogen into the α – titanium alloy VT5 at 650 o C and a concentration of 0.1% by weight leads to a decrease in the rate of secondary creep from 1.4 to 3.1 times and an increase in the time at the rupture time from 2.1 to 3.5 times, while no noticeable effect of hydrogen on the ultimate elongation strain at the rupture time has detected. Experimental data on simultaneous torsion and tension of tubular specimens under creep conditions showed that significant rotation angles from 150 to 260 degrees are observed for the titanium alloy VT1 – 0 at 550 o C with the working length of the tubular specimen of 130 mm, while an increase in the ratio of normal stress to tangential stress leads to an increase in the elongation rate and a decrease in the rotation angle rate. Thus, at the same value of the maximum normal stress equal to 100 MPa, an increase in the ratio of the normal stress to the tangential stress from 1 to 3 leads to an increase in the elongation rate by 1.8 times and a decrease in the angle rate by 2.2 times. And also at the same value of the doubled maximum tangential stress equal to 100 MPa, an increase in the ratio of normal stress to tangential stress from 1 to 3 leads to an increase in the elongation rate by 2.4 times and a decrease in the angle rate by 2.1 times. Acknowledgements This work was partially suppo rted by the Russian Foundation for Basic Research (grant 20−08−00387). References Kolachev, B., Elagin, V., Livanov, V., 2001. Metal Science and Heat Treatment of Non Ferrous Metals and Alloys. Institute of steels and alloys, Moscow, pp. 176−260. Lokoshchenko, A., Nazarov, V., Il'in, A., Mamonov, A., 2008a. Analysis of the Creep and Long Term Strength of VT6 Titanium Alloy with Preliminarily Injected Hydrogen. Materials Science 44(5), 700−707. Lokoshchenko, A., Nazarov, V., Il'in, A., Mamonov, A., 2008b. Experimental and Theoretical Study of the Effect of Hydrogen on the Creep and Long Term Strength of VT6 Titanium Alloy. Russian Metallurgy 2, 142−147. Nazarov, V., 2012. Influence of Hydrogen on Creep and Rupture of Titanium Alloys. Industrial Laboratory. Diagnostics of Materials 78(12), 59−65.