Creep lifetime prediction of oxide-dispersion-strengthened nickel-base superalloys: A micromechanically based approach
- Inst. For Solid State and Materials Research, Dresden (Germany)
- Univ. of Erlangen-Nuernberg, Erlangen (Germany). Inst. for Materials Science
The high-temperature creep behavior of the oxide-dispersion-strengthened (ODS) nickel-base superalloys MA 754 and MA 6000 has been investigated at temperatures up to 1,273 K and lifetimes of approximately 4,000 hours using monotonic creep tests at constant true stress {sigma}, as well as true constant extension rate tests (CERTs) at {dot {var_epsilon}}. The derivation of creep rupture-lifetime diagrams is usually performed with conventional engineering parametric methods, according to Sherby and Dorn or Larson and Miller. In contrast, an alternative method is presented that is based on a more microstructural approach. In order to describe creep, the effective stress model takes into account the hardening contribution {sigma}{sub p} caused by the presence of second-phase particles, as well as the classical Taylor back-stress {sigma}{sub p} caused by dislocations. The modeled strain rate-stress dependence can be transferred directly into creep-rupture stress-lifetime diagrams using a modified Monkman-Grant (MG) relationship, which adequately describes the interrelation between {dot {var_epsilon}} representing dislocation motion, and lifetime t{sub f} representing creep failure. The comparison with measured creep-rupture data proves the validity of the proposed micromechanical concept.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 438551
- Journal Information:
- Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Vol. 27, Issue 12; Other Information: PBD: Dec 1996
- Country of Publication:
- United States
- Language:
- English
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