Effect of Aluminum Addition on Microstructure and Oxidation Performance of Cast Irons

The cast iron that comes with a ferritic matrix are mainly used for the application that require higher temperature working conditions, such as exhaust manifold. However, the higher demand for obtaining material show higher efficiency led the material production companies and manufacturers to use Ni-resist austenitic ductile cast irons and stainless steels, which are relatively more expensive than cast iron and considered as the main challenge for them. This challenge motivated the manufacturer to develop new alloys that show high temperature resistance, higher resistance for oxidation, and lower in cost. In this study, works postulates the resistance of the phases formed due to oxidation of the cast iron alloy with the ratio of (0 to 4 wt% Al) based on the oxidation, X-ray diffraction, and optical microscopy. The oxidation mechanisms of the referred alloy were presented at the range of high temperature (700-900 ℃). The results showed the temperature of oxidation and Al content are linearly proportional. Low resistance for the oxidation was noticed at a lower value of oxidation temperature. The oxidation resistance was characterized by the formation of FeO, Fe2O3 and Fe3O4. The performance of the alloyed cast-irons was significantly enhanced as the content of Al increased. As the content of Al increased, the scale thickness reduced gradually. The behavior of the alloyed cast-irons oxidation kinetic for all conditions of the test was parabolic in its nature at various constants of parabolic rates.