Zachary B. Towner, Santosh B. Narasimhachary, Phillip W. Gravett, Richard W. Neu, Christopher L. Muhlstein, Ashok Saxena
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Creep crack growth experiments were performed at 750°C, 850°C, and 950°C on nominally 3 and 12.7 mm thick compact type specimens of alloy 247LC-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 750°C. Cracks grew by formation, growth, and coalescence of cavities on interdendritic carbides in both the primary crack plane and normal to said plane at 850°C and 950°C. The variability in the crack growth rate was higher in thicker specimens, but the mean creep crack growth rate versus Ct relationship in 247LC-DS was neither sensitive to test temperature ≥850°C nor specimen thickness. Quantitative relationships between da/dt and Ct were derived for mean, upper, and lower bound creep crack growth rate trends.
期刊介绍:
Fatigue & Fracture of Engineering Materials & Structures (FFEMS) encompasses the broad topic of structural integrity which is founded on the mechanics of fatigue and fracture, and is concerned with the reliability and effectiveness of various materials and structural components of any scale or geometry. The editors publish original contributions that will stimulate the intellectual innovation that generates elegant, effective and economic engineering designs. The journal is interdisciplinary and includes papers from scientists and engineers in the fields of materials science, mechanics, physics, chemistry, etc.