Background: Hot corrosion is a phenomenon seen in gas turbines using residual fuel oils,
which contains vanadium. Austenitic stainless steels are ones of the most used materials in components
and devices of boilers, gas turbines and furnaces burning contaminated fuel oil. The materials selection is
made in great extend due to a good corrosion resistance and low cost. Some works have been done in
order to determine the performance of stainless steels under molten salts at high temperatures, obtaining
good corrosion resistance, that is why the evaluation of the corrosion rate and the type of corrosion suffered
by two austenitic stainless steels is important in order to determine their possible selection under hot
Methods: The corrosion resistance of the materials was obtained applying the linear polarization resistance
and the electrochemical impedance spectroscopy during 100 hours. In order to determine some aspects
of the corrosion mechanism, potentiodynamic polarization measurements were also obtained.
Physical and Chemical analyses were carried out utilizing the Scanning Electron Spectroscopy and the Xray
Results: It was determined that AISI-316H developed a Cr2O3 layer, which was dissolved by the electrolyte,
so that, this alloy suffered intergranular corrosion due to the precipitation of Cr23C6, such as it has
been reported extensively. AISI-347H presented the Kirkendall effect, suffering an important depletion of
Fe and in a less extent of Cr, leading to a mixed corrosion process. These behaviors were corroborated
with the electrochemical techniques.
Conclusion: AISI-316H presented intergranular corrosion, whereas AISI-347H suffered a mixed corrosion
type, observing areas indistinctively localized and uniformly corroded. The electrochemical techniques indicated
that AISI-316H is more corrosion resistance and both alloys were diffusion controlled systems.