Abstract
High temperature fatigue properties of the Inconel718 superalloy specimens to which a Co-based wear resisting alloy, Stellite31, was coated by the Micro Spark Coating (MSC) method, were investigated as well as the microstructural stability. It was shown that the microstructure of the coatings was almost stable even after the long term isothermal aging at 480℃ by 1000 hrs in air, while it changed significantly at 650℃. In the latter, increase in hardness was seen, associated with an evolution of oxide rich phases. The fatigue properties of the coated specimens revealed a complex behavior depending on the loading level and test temperature: in high cycle regime the coated specimens showed shorter fatigue lives than the Incone1718 substrate, while the former longer than the latter in low cycle regime. It was suggested that high temperature fatigue properties were influenced by two phenomena: one was the prior substrate surface characterization that might be affected by MSC process; and the other was a load transfer capability of the coated area, dependent on the test temperature and exposure time.
