Microstructural Characterization of the White Etching Layer in Nickel-Based Superalloy

Microstructural characterization of the white etching layer (WEL) formed during milling in a fine-grained IN100 Ni-based superalloy was conducted. The microstructure of the layer depended on milling parameters, and under typical machining conditions, where moderate surface speed was used, the white layer exhibited nanostructure character. Fast surface speed produced partial amorphization of the outermost layer. Limited notched low cycle fatigue (LCF) testing was performed, and it was demonstrated that the fatigue properties deteriorated significantly in the specimens where WEL was present in the notch-root surface.