Abstract
The article presents the results of an experimental study of the structure and strength properties of a heat-resistant nickel alloy of the CrNi65CoMoWAlB grade. This alloy is used for the manufacture of rotor blades for turbines of gas turbine plants. Ensuring the reliability of highly loaded parts is an integral part of the production process. For analysis, samples were taken with different structural states, which were cut from two different batches of blanks for the manufacture of rotor blades. Both batches of billets underwent preliminary hot plastic deformation (forging) and heat treatment (austenization and aging). Samples from the first batch had a reference structure with a uniform distribution of hardening phases, the second batch of samples had a defective structure with a pronounced uneven grain size, stitching and uneven distribution of hardening phases. A detailed analysis of the microstructure and mechanical characteristics of the alloy was carried out both using standard methods and non-standard research methods. Conducting microstructural analysis and relaxation tests using microsamples cut from zones with increased inhomogeneity showed that the standard approach recommended by standard does not reflect the real picture with a negative change in the microstructure of the material and is not sensitive to the presence of microdefects in the alloy structure. The study made it possible to establish the influence of the uneven distribution of hardening phases and inequigranularity on the mechanical characteristics. The limit of microplasticity and long-term strength turned out to be especially sensitive indicators. A significant decrease in the value of microplasticity and time to failure was recorded for a sample with a substandard alloy structure. The detected changes in the structural and strength properties in the material can significantly reduce the performance or lead to failures of critical parts.
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