Aluminide diffusion coatings enhance carburization and oxidation resistance of iron and nickel based alloys by formation of iron and nickel aluminides which extends the life of furnace alloys and fixtures. As a part of a large project in the Center for Heat Treating Excellence (CHTE), an aluminized coating on RA330 was studied by a hot dip process followed by diffusion heat treatment. Samples of RA330 steel were dipped in pure liquid aluminum at 700 °C for 10 minutes. After dipping, four samples were given an additional diffusion treatment. To predict the developed phases, computational analysis was used and the results were compared with the experimental data.

Extension of the service life for high temperature structural alloy RA602CA is the goal for the project described in this paper. The performance of alloy RA602CA and aluminized RA602CA in a gas carburization furnaces were studied for periods up to two years. Aluminizing treatments (widely used in aerospace industry, especially in turbine blade applications) were also studied in this project. Carbon has very low solubility in alumina, so aluminizing could be a good method for protecting RA602CA alloys. Microstructural development during the carburizing process is presented, and the degradation of chromium oxide as well as alumina oxides is identified. The weight gain of RA602CA compared to similar alloys is discussed.