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Steam Oxidation of Martensitic Steels and of Ni-Base Alloys: Comparison of Lab Tests with Operating Power Plants
Ist Teil von
Oxidation of metals, 2014-08, Vol.82 (1-2), p.113-122
Ort / Verlag
Boston: Springer US
Erscheinungsjahr
2014
Link zum Volltext
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
The oxidation stability of materials for high-temperature power plants is usually tested in the laboratory with equipment at constant temperatures. These tests are valuable for a quick assessment of different steels and alloys. However, in reality steam power plants operate at varying temperatures due to changing demands (day/night, summer/winter, outages, etc). Therefore, it is advantageous necessary to test materials in operating power plants. In the past, this was done for a large variety of materials, but often it is not possible to compare these results to those of lab tests. The exposure time was up to about 5,000 h in lab tests and about 16,000 h in power plant tests. In the present study a method was developed, that allows determination of rate constants for the growth of oxide scales when temperatures are fluctuating. It was found that martensitic steels yield similar results in lab and in plant tests, i.e., steam pressure and steam velocity do not influence scale growth. In contrast, Ni-base alloys show considerable higher oxidation rates in plant tests than in lab tests. The reason for this behaviour is not yet clear and has to be investigated further.