Study of operational destruction of the GTP compressor disk of alloy VT8

Ospennikova O.G., Naprienko S.A., Lukinа E.A.
UDC
669.295
DOI
10.18577/2307-6046-2018-0-12-97-106
Article PDF (Russian) (1.38 MB)
How to cite
Ospennikova O.G., Naprienko S.A., Lukinа E.A. Study of operational destruction of the GTP compressor disk of alloy VT8 // Proceedings of VIAM. 2018. No. 12. DOI: 10.18577/2307-6046-2018-0-12-97-106. URL: https://test.viam.ru/en/journal/2018/12/11
Keywords
VT8, compressor disk, electronic microscopy, fractography, corrosion cracking.
Abstract

In the course of the work, the causes of cracks formation on a large-size item (compressor disk) of VT8 alloy, working as a part of GTU, are investigated. Visual inspection of the disc was carried out. At the rear end of the disk hub there are two cracks that bend around the end of the hub in a perpendicular direction and have an outlet to the inner and outer surfaces of the disk. On the facet, close to a development of cracks are observed in dark areas of the surface. Inspection of the disk surface and microstructural studies have shown that the item was exposed to temperatures above 400°C for a long time. Near the chamfer, the thinning of some parts of the silver coating of the inner surface of the disk hub was revealed. It is most likely that there was mechanical abrasion of the coating in this area. Near the chamfer, the thinning of some parts of the silver coating of the inner surface of the disk hub was revealed. It is most likely that there was mechanical abrasion of the coating in this area.

The study of the fracture surface revealed brittle facets on the fracture and a large number of branching secondary cracks. Multiple cracking found on the microsection made across the failure surface. The material composition of the dark areas on the surface of the chamfer includes silver, oxygen and chlorine.

Samples of the alloy ВТ8 were tested in static loading in a 2% HCl solution according to STO 1-595-30-468-2015. It is shown that the type of the fracture surface of the experimental and operational samples is identical. The results of studies indicate that the development of cracks occurred on the mechanism of stress corrosion cracking in the presence of chlorine ions. Thermodynamic analysis is carried out. It is shown that the reaction of the interaction of silver with chlorine and hydrochloric acid occurs at temperatures of 150-2000&

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