| Title |
A Study on the Oxide Scale of the Long Term Serviced 12%Cr Boiler Tube Steel |
| Authors |
김범수(Beom Soo Kim) ; 민택기(Taek Ki Min) |
| DOI |
http://dx.doi.org/10.6110 /KJACR.2012.24.3.281 |
| Keywords |
산화스케일 ; 12Cr강 튜브 ; Fe-Cr층 산화스케일 ; Fe2O3 ; Fe3O4 Oxide scale ; X20CrMoV12.1 튜브 ; Fe-Cr spinnel ; Hematite ; Magnetite |
| Abstract |
The internal oxide scale of twelve superheater and reheater tubes were tested which were serviced for 30,000～120,000 hours in thermal power plants. The oxide scale was formed in three layers. The Cr-rich area was observed beneath the original metal surface. The hematite (Fe2O3) phase was formed on the outer surface. The intermediate layer was magnetite (Fe3O4). The thickness of Cr-rich layer was about half of the total scale. All layers grew during the operation hour of the plant. The thickness of thickest scale was 0.2mm in superheater tubes. This can increase the tube metal temperature about 7℃ more than initial state. 7℃ tube metal temperature can reduce tube life about 30%, but the boiler tube’s design margin is big enough therefore it has been analyzed that it would not effect on the life span. |