Microstructural aspect and oxidation resistance of an aluminide coating on 310 stainless steel

Abstract Surface alloying of Al into AISI 310 austenitic stainless steel to increase its high temperature oxidation resistance was attempted by employing pack cementaion process. After aluminization, the surface microstructure mainly consisted of an outer high aluminum-containing layer, an intermediate intermetallic compound layer and a ferritic stainless steel layer followed by the austenitic substrate. Oxidation resistances of AISI 310 stainless steel with or without aluminization treatment were evaluated by conducting thermal gravimetric analysis (TGA) in air at 700 and 1000°C. At these temperatures, parabolic oxidation behavior was observed for all the specimens investigated. Enhanced oxidation resistances (increased with increasing Al content) were found for the aluminized layers as compared with 310 stainless steel substrate. After TGA, the oxides formed on the specimen surfaces were identified by X-ray diffraction analyses. The results showed that the oxides formed on 310 stainless steel were composed of an outer spinel of Fe/Mn oxide and an inner layer of chromium oxide. For aluminized stainless steel specimens tested, the main constituent of the oxide layer was Al 2 O 3 .