Abstract
Fe-(9, 19, 28, 37) wt. %Cr alloys were corroded at 700 and 800 °C for 70 h under 1 atm of N2, 1 atm of N2/3.2%H2O mixed gas, and 1 atm of N2/3.1%H2O/2.42%H2S mixed gas. In this gas composition order, the corrosion rate of Fe-9Cr alloy rapidly increased. Fe-9Cr alloy was always non-protective. In contrast, Fe-(19, 28, 37) wt. %Cr alloys were protective in N2 and N2/3.2%H2O mixed gas because of the formation of the Cr2O3 layer. They, however, became nonprotective in N2/3.1%H2O/2.42%H2S mixed gas because sulfidation dominated to form the outer FeS layer and the inner Cr2S3 layer containing some FeCr2S4.
Highlights
Fe-Cr alloys are widely used as high-temperature structural materials
When the Cr content in iron was ~5 wt. %, triple oxide layers such as Fe2 O3 /Fe3 O4 /FeO formed, and the oxidation rate was mainly controlled by the growth rate of FeO that formed on the alloy side [1]
When Fe-9Cr alloy corroded at 700 and 800 ◦ C in N2 and N2 /3.2%H2 O gas, thick, porous oxide scales formed, which consisted of the outer iron oxide layer and the inner (Fe,Cr) mixed oxide layer
Summary
Fe-Cr alloys are widely used as high-temperature structural materials. They oxidize when exposed to air or oxygen at high temperatures. %, a mixed spinel, Fe(Fe,Cr) O4 , formed, which decreased the oxidation rate significantly. When Fe-Cr alloys were exposed to S2 gas at 1 atm, an FeS layer formed below 1.86 wt. Fe-Cr alloys with high Cr contents displayed insufficient corrosion resistance. This is attributed to the fact that sulfidation rates of common metals are 10–100 times faster than oxidation rates because the sulfides have much larger defect concentrations and lower melting points than the corresponding oxides [5]. The corrosion of conventional oxidation-resistant alloys by water vapor and H2 S gas has been a serious problem [3]. The high-temperature corrosion of Fe-Cr alloys, which has not been adequately investigated before
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
