HIGH CYCLE FATIGUE PROPERTIES OF NICKEL-BASE ALLOY 718

摘要

We investigated the fatigue properties of nickel-base Alloy 718 with fine- and grain-coarse grains. In the fine-grain alloy, the fatigue strength normalized by the tensile strength was 0.51 at 10 cycles. In contrast, the fatigue strength of the coarse-grain alloy was 0.32 at the same cycles, although the fatigue strengths in the range from 10~3 to 10~5 cycles are the same for both alloys. The fracture appearances fatigued at around 10~6 cycles showed internal fractures originating from the flat facets of austenite grains for both alloys. The difference in fatigue strength at 10~7 cycles between the fine- and coarse-grain alloys could be explained in terms of the sizes of the facets from which the fractures originated.