Fatigue behavior of uncoated and MCrAlY-coated DS nickelbased superalloys pre-exposed in hot corrosion condition

摘要

The effects of a MCrAlY coating on low-cycle fatigue(LCF) behavior of directionally solidified(DS)nickle-based superalloy DZ125 were investigated. Before the fatigue testings, the specimens were pre-exposed in high-temperature hot corrosion(HTHC) environment generating by a burner rig at 850 ℃. The results show that the coating in hot corrosion condition has beneficial effects on the fatigue resistance of superalloy. Under corrosion condition, the MCrAlY-coated specimens tested have higher fatigue lives than the uncoated specimens at the same stress level. The coating failure results from fatigue process and numerous fatigue cracks were nucleated at the specimen surface, only one main crack propagates inward and the secondary cracks away from the fracture surface are perpendicular to the loading orientation.