It has been known for some time that alloying of steels with aluminum improves sulfidation and oxidation resistance. The behavior of a number of such alloys in high-temperature H2S-H2 environments has been investigated; results indicate that some of them may have practical applications in petroleum refining equipment.
The studies included alloys of iron-aluminum, iron-chromium-aluminum, and iron-chromium-nickel-aluminum. The article presents the results of both corrosion and micrographic investigations.
Addition of aluminum in the order of 2 percent appreciably increases the corrosion resistance of 13 percent chromium steel but has negligible effect on the corrosion of 5 percent chromium steel. About 4 percent aluminum is needed for effective increase of corrosion resistance of the normally austenitic 18-8 stainless steels; however, the alloy becomes ferritic. The most resistant alloys tested resulted from the addition of aluminum to the higher chromium-nickel steels with sufficient nickel present to retain the austenitic structure. 6.2.1
