Oxidation and Carburization for INCONEL alloy 617

Oxidation and Carburization : The resistance of INCONEL alloy 617 to cyclic oxidation at 2000°F (1095°C) is shown in Figure 9. The tests were performed on specimens of thin strip and consisted of cycles of exposure to temperature for 15 minutes followed by cooling in still air for 5 minutes. The results demonstrate the ability of the alloy to form and retain a protective surface oxide under conditions of extremely severe thermal cycling. The results of a similar test at 2100°F (1150°C) are shown in Figure 10. The specimens of thin strip were exposed to the test temperature in 50-hour cycles with weight loss determined after each cycle. The resistance of alloy 617 and other high strength, heat-resistant alloys to static oxidation in moist air at 1832°F (1000°C) is shown in Figure 11. The excellent resistance of alloy 617 to oxidation results from the alloy’s chromium and aluminum contents. At elevated temperatures, those elements cause the formation of a thin, subsurface zone of oxide particles. The zone forms rapidly upon exposure to high temperatures until it reaches a thickness of 0.001 to 0.002 in. (0.025 to 0.05 mm). The oxide zone provides the proper diffusion conditions for the formation of a protective chromium oxide layer on the surface of the metal. It also helps to prevent spalling of the protective layer. INCONEL alloy 617 has excellent resistance to carburization. Table 9 compares alloy 617 and some other carburization-resistant alloys in a gaseous carburizing environment at 2000°F (1095°C). The weight-gain measurements indicate the amount of carbon absorbed during the test period. Table 10 shows the superiority of alloy 617 over alloys of similar strength in a gascarburization test at 1800°F (980°C).