HIGH TEMPERATURE WEAR BEHAVIOR OF HOT-DIP ALIMINIZED INCONEL 718

Abstract

Superalloys are used in a wide range of applications in aviation, aerospace and nuclear energy industries. Inconel 718 is a nickel-based superalloy that provides remarkable mechanical properties and surface stability at elevated temperatures. The surface of Inconel 718 can be modified by several techniques to further improve its surface properties such as oxidation and wear resistance. Among several surface modification techniques, hot-dip aluminizing ( HDA) is a highlighted one as an easy and cost-effective high temperature coating (HTC) technique that utilize diffusion mechanisms. In this study, effect of HDA and subsequent diffusion annealing (DA) on high temperature wear behavior of Inconel 718 superalloy was investigated. Inconel 718 samples were first hot-dip aluminized in a molten Al-12wt.%Si bath and subjected to diffusion annealing. Morphological and structural analyses were carried out by using SEM-EDS examinations and XRD analyses. Ball-on-disc wear tests of the bare, HDA and HDA+ DA samples were conducted at room temperature, 300 degrees C and 600 degrees C. The results revealed that aluminum rich and nickel rich aluminide phases were formed after HDA and HDA+ DA processes, respectively. Wear tests results showed that the wear rate of the HDA+DA sample was approximately three times lower than the HDA samples and four times lower than the bare Inconel 718 at room temperature. With increasing temperature, the wear rate of the bare alloy continuously decreased, while higher wear rates were observed for HDA+DA samples at elevated temperatures with respect to that of room temperature. Dominant wear mechanism was discussed based on the wear track morphology examined by SEM.