CONSIDERATION OF THE EFFECT OF CRYOGENIC TEMPERATURES ON THE FATIGUE OF RESOURCED ALLOYS BY MEANS OF ACOUSTIC EMISSION

The article provides an example of the implementation of fatigue life calculation, which uses a multi-level acoustic emission model to obtain the parameters included in the equation of the kinetic concept of strength. Using the data obtained during acoustic emission tests for crack resistance of titanium alloy samples PT-3V at three temperature levels: 293, 77 and 4 K, concentration-kinetic indices of XAE strength and YAE were calculated, which carry information about the unique nature of damage accumulation for this object in the form of a structural γ coefficient included in the Zhurkovthermoeluktuation equation. These parameters were selected from the deformation sites of the samples, which, according to the results of microstructural analysis, showed the presence of many microcracks with different directions of propagation, which were associated with the accumulation of destructive damage in the elastoplastic region. The obtained kinetic parameters: the energy of activation of U0 destruction and the γ parameter were used to estimate the fatigue life of the samples using a formula that takes into account the sinusoidal change in stresses during cyclic loading and is also based on the kinetic concept of strength. Taking into account the changes in temperature in the cycle due to the thermoelastic effect, it was possible to obtain fatigue curves similar to those obtained for the titanium alloy at the same temperatures. Fatigue curves of similar properties of titanium alloy destroyed by cyclic loading at the same temperatures were used for comparison. It has been proved that the slope of fatigue curves, as an individual characteristic of the material, is determined by the concentration-kinetic values of XAE and YAE obtained during static tests.