Rezumat
CZU 621.165.73:620.19
DOI https://doi.org/10.5281/zenodo.1228855
The article describes results of studies of the influence of periodic removal (by grinding) of a thin surface metal layer of low-alloy steels used for the fabrication of shrunk-on discs of middle-pressure and low-pressure steam turbine rotors on the life of standard samples in conditions of stress corrosion cracking (SCC). It is established that the optimum magnitude of the removal of the metal layer is 0.1 mm and the optimum intervals are from 50% to 65% of the incubation period. It is proved that the removal of the metal layer, which accumulates microdamages under SCC, almost completely restores the steel disk resource in this type of damage. It is found that the nature and mechanism of the SCC samples under test conditions and the SCC of full-scale discs are similar. It is also stated that both single and repeated removal of the surface metal layer by periodic grinding almost comple-tely restores the original disk resource of steel samples defined by their long-term corrosion resistance under SCC. It proves the purposefulness of the periodic removal of the surface metal layer of localized corrosion-damaged disc areas of steam turbines currently used at power plants.
Keywords: stress corrosion cracking, low-alloy steels, rotor shrunk-on disc, steam turbine, life of samples, surface layer of metal, periodic removal, phase transition zone.