Senior engineer, Westinghouse Research Laboratories, Pittsburgh, Pa.
Ohio State University, Columbus, Ohio
Pages: 21 Published: Jan 1976
A fracture mechanics approach was used to study high-temperature creep crack propagation. Crack growth rates were correlated with the C*-parameter which is an energy rate line integral. For materials conforming to a nonlinear stress and strain rate relationship in the steady-state creep range, specifically, those which can be properly idealized as purely viscous (negligible elastic and transient creep effects), C* characterizes the crack tip stress and strain rate fields.
Crack growth rate tests were conducted in the creep range on a discaloy superalloy at 1200°F (920 K). Two specimen geometries were tested, a center cracked panel and a compact geometry, to establish the geometry independence of this approach. The results showed that crack growth rate correlated with the C*-integral, while other parameters (K and nominal stress) failed to adequately characterize crack growth rate.
crack propagation, stress analysis, mechanical properties, fracture properties, crack initiation, creep rate
Paper ID: STP33943S