Short-term high-temperature creep of Grade 5 titanium alloy heated in air and argon

The paper presents the results of studying the deformation of samples of the alloy Grade 5 while they are heated to temperatures ranging between 900 and 1350 K with constant tensile stresses of 4.45, 6.91 and 9.36 MPa, which is significantly below the yield stress of the alloy at the test temperatures (σT ≥ 34 MPa). Under these conditions, the deformation occurs due to the mechanism of short-term creep. During testing, the samples are heated in air and argon environments. The results are compared with the results obtained earlier in similar studies for Grade 2 commercially pure titanium and Ti-5AL. The investigation has revealed a qualitative similarity of the effect of environment on the processes of creep deformation in Grade 2 commercially pure titanium, Ti-5AL alloy, and Grade 5 alloy. Herewith, all the alloys under study have close values of activation energy (from 250 to 320 kJ/mol). The experiments have shown that, as compared to previously studied alloys, Grade 5 alloy has higher temperatures of the onset of creep deformation and lower creep rates. Processing of the results has allowed us to evaluate the empirical coefficients for Grade 5 alloy in two dependences obtained earlier for the Ti-5AL and Grade 2 alloys. One dependence relates the creep rate to the heating temperature, tensile stress, and creep activation energy; the other one relates the creep deformation onset temperature (residual creep deformation within 1 hour of holding is 0.2%) to the conventional short-term creep limit.