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The high temperature oxidation of 11% chromium steel: Part II – Influence of flow rate
Author(s) -
Segerdahl K.,
Svensson J.E.,
Johansson L.G.
Publication year - 2002
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/1521-4176(200207)53:7<479::aid-maco479>3.0.co;2-h
Subject(s) - chromium , vaporization , chemistry , oxide , metallurgy , alloy , nuclear chemistry , analytical chemistry (journal) , materials science , environmental chemistry , organic chemistry
The oxidation of type X20 CrMoV 11 1 steel at 600°C in the presence of dry O 2 and O 2 + 10 or 40% H 2 O was investigated. The flow rate was varied between 0.25 to 10.0 cm/s. Exposure time was 168 hours. The oxidized samples were investigated gravimetrically and by a number of surface analytical techniques including grazing angle SEM/EDX, GDOES and XRD. Oxidation is strongly influenced by pH 2 O and flow rate. In O 2 + H 2 O environment at 600°C, the protective Cr‐rich α‐(Cr,Fe) 2 O 3 oxide loses chromium by vaporization of CrO 2 (OH) 2 . When chromium loss is limited (e. g., in 10% H 2 O and in 40% H 2 O at low flow rates) the supply of chromium from the alloy compensates for chromium vaporization and the oxide retains its protective properties, resulting in slow oxidation. In 40/60 H 2 O/O 2 and high flow rates chromium evaporation becomes so rapid that the protective properties of the oxide are lost and a thick duplex (Fe 2 O 3 /Fe 2 CrO 4 ) scale develops.