The heat resistant cast irons have been used extensively in the industry, so it must be studied on the high temperature property. The objective of this study is to investigate the high temperature oxidation property of aluminum-based flake graphite heat resistant cast irons. The effects of flake graphite morphology and various alloy additions (Al-C-Si-Mn) on the oxidation resistance (weight variation, oxidation rate) at different temperatures (673K, 873K, 1073K, 1273K) of aluminum-based cast irons have been evaluated in this study by using the specimen size of ψ20 mm× 30 mm for the oxidation test. Meanwhile, we observed the metallographic microstructure changes by the metallurgical microscope to analysis and evaluate the change of oxidation resistance. According to the results of this study know that: (1) As a result of cast irons used contains graphite which will cause various degrees of decarburization at the high temperature, so the oxidation resistance of specimens with annealed treatment is better than the as-cast specimens. (2) During the transient stage of oxidation up to 100 hr at 673K, the variations of weight of the specimens have been changed in evidence and the rate of oxidation are rising. It contains 2.5% Al and 0.5% Mn of low aluminum flake graphite heat resistant cast irons with annealed treatment shows better oxidation resistance. (3) During the transient stage of oxidation up to 50 hr at 1073K, the loss of weight for all specimens is caused by decarburization. High aluminum heat resistant case irons contains 22% Al and 0.7% Mn of as-cast or annealed to show better oxidation resistance. (4) The relationship between the variation of weight and the rate of oxidation are: The rate of oxidation becomes smaller when the variation of weight is small, and the rate of oxidation becomes larger when the variation of weight is large. If the rate of oxidation becomes zero, it shows that the protective oxide film has been formed. For the aluminum-based flake graphite heat resistant cast irons when the aluminum contents increased then the flake graphite in the matrix changed from coarse to fine form gradually.
Aluminum-based flake graphite heat resistant cast ion 'oxidation resistance' metallographic microstructure