The results of an experimental research of the long-term combined strength of the EI437BU-VD heat resisting deformable nickel alloy used for disks and shafts of gas turbines are presented. The experimental data was obtained as a result of creep-rupture tests of thin-walled tubular samples under plane tension for various relationships between the axial tensile force and torque at 650 °С. The results of the tests are used to determine parameter ? in a two-parameter criterion of equivalence of the tensions, earlier introduced by the present authors. It is shown, that the obtained experimental data are approximated by a stress rupture curve with a breaking which testifies to a possible change of character of shattering depending on the longevity. Parameter values of ? for each section of the broken stress rupture curve (?
1 and ?
2) are determined. The comparative assaying of estimations of a variance of experimental data concerning a calculated stress rupture curve in equivalent stresses has shown, that the two-parameter criterion with the obtained parameter values of ? (?
1 and ?
2) more precisely and adequately represents long-term durability of the alloy under complex tension, than the widely used Mises - Hencky's criterion.
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