Document Type
Article
Publication Date
7-10-2024
Keywords
creep crack growth, directionally-solidified Ni-base superalloy, time-dependent fracture mechanics
Abstract
Creep crack growth experiments were performed at 750C, 850C, and 950C on nominally 3 and 12.7 mm thick compact type specimens of alloy 247 LC-DS, a Ni-base superalloy used for hot-section gas turbine blades. The primary crack plane was transverse to the solidification direction. The crack path– microstructure interaction was characterized. Crack growth occurred in a creep-ductile manner and data analyses utilized time-dependent fracture mechanics. No measurable crack growth occurred at 750C. Cracks grew by formation, growth, and coalescence of cavities on interdendritic carbides in both the primary crack plane and normal to said plane at 850C and 950C. The variability in the crack growth rate was higher in thicker specimens, but the mean creep crack growth rate versus Ct relationship in 247 LC-DS was neither sensitive to test temperature ≥850C nor specimen thickness. Quantitative relationships between da/dt and CT were derived for mean, upper, and lower bound creep crack growth rate trends.
Citation
Towner ZB, Narasimhachary SB, Gravett PW, Neu RW, Muhlstein CL, Saxena A. Creep crack growth in alloy 247LC-DS. Fatigue Fract Eng Mater Struct. 2024; 47(10): 3546-3560. doi:10.1111/ffe.14385
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