Low Cycle Fatigue Fracture Mechanism of a Modeling Specimen with Cooling Film Hole of DD6 Single Crystal Superalloy

Abstract:

The flat plate specimens of nickel-base single crystal superalloy DD6 with different numbers of laser-processed cooling film holes were used to study the low cycle fatigue properties at 900 oC. The test data and SEM fracture images were analyzed. The results show that the life of single-hole specimens is ten times of that of the close-spaced holes specimens in the same experimental condition. A number of microcracks are found around the cooling film hole and the destruction of the specimens with cooling film holes is a typical multi-source rupture. The cracks propagate along the {001} planes for single-hole specimens and the middle holes of the close-spaced holes specimens, but the cracks extend along a plurality of slip plane for up and bottom holes of the specimens with close-spaced holes.

Key words:nickel-base single crystal superalloy; modeling specimen; low cycle fatigue