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.

The heat-treating industry is in need of heat-treatment furnace materials and fixtures that have a long service life and reduced heat capacity. Failure mechanisms on the effect of prolonged exposure to carburization heat treatment have been investigated. RA330, RA602CA, 304L, 316L and Inconel 625 alloys were selected to study the anti-corrosion properties. The alloys were exposed to 0.7%C carburizing atmosphere at around 900°C for 3 months, 6months, and 12months. Based on microstructural analysis of components that were used until failure in carburization furnace application, it was found that the primary reason for failure was the excessive carburization that leads to “metal dusting” and subsequent cracking. In addition, metallographic analysis indicated that “flake offs” of Fe-Cr-Ni alloys were mainly graphite and chromium carbides. In this paper the failure analysis of industrial components will be presented. In addition, the preliminary analysis of microstructural development during long term exposure experiments in an industrial carburizing furnace will be presented. These samples were characterized using optical and scanning electron microscope and x-ray diffraction.