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Corrosion Behavior of Weldable Fe-Al Alloys in Oxidizing-Sulfidizing Environments

Published

Author(s)

Stephen W. Banovic, J N. DuPont, A R. Marder

Abstract

Weld overlay coatings are typically used to protect existing low alloy steel water-wall panels from accelerated sulfidation attack in fossil-fired boilers with advanced low NOx burners. A material system presently under consideration for use as a cladding is Fe-Al. Previous corrosion studies in very aggressive oxidizing/sulfidizing gaseous environments at high temperatures have shown intermetallic compositions (with >10 wt % Al) to perform well. However, these high aluminum content alloys cannot be readily applied as weld overlays due to hydrogen cracking susceptibility. Moreover, the lower aluminum alloys, which are weldable, lack the detailed corrosion studies in mixed gas compositions considered necessary in order for them to be commercially installed. Therefore, to permit use of weldable Fe-Al deposits as protective coatings, investigation of their corrosion behavior was initiated in environments representative of low NOx gas conditions (i.e., low partial pressures of O2, high partial pressures of S2, moderate temperatures). Through an integrated experimental approach involving thermogravimetric techniques, post-exposure metallographic examination of the corroded samples, and detailed chemical microanalyses of the reaction scales, the corrosion behavior of the alloys was described as a function of the aluminum content (from 0 wt % Al to 12.5 wt % Al) and temperature (500 degrees C to 700 degrees C).
Citation
Corrosion Behavior of Weldable Fe-Al Alloys in Oxidizing-Sulfidizing Environments

Keywords

corrosion, iron alloys, iron-aluminum alloys, weld overlay coatings

Citation

Banovic, S. , DuPont, J. and Marder, A. (2001), Corrosion Behavior of Weldable Fe-Al Alloys in Oxidizing-Sulfidizing Environments, Corrosion Behavior of Weldable Fe-Al Alloys in Oxidizing-Sulfidizing Environments (Accessed February 23, 2024)
Created January 1, 2001, Updated February 17, 2017