Creep lifetime prediction of oxide-dispersion-strengthened nickel-base superalloys: A micromechanically based approach

Journal Article · Sun Dec 01 04:00:00 EST 1996 · Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science

DOI:https://doi.org/10.1007/BF02595635· OSTI ID:438551

Heilmaier, M ^[1]; Reppich, B ^[2]

---

1. Inst. For Solid State and Materials Research, Dresden (Germany)
2. 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, Journal Name: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science Journal Issue: 12 Vol. 27; ISSN MMTAEB; ISSN 1073-5623
• Country of Publication: United States
• Language: English

Related Subjects

20 FOSSIL-FUELED POWER PLANTS
33 ADVANCED PROPULSION SYSTEMS
36 MATERIALS SCIENCE
CREEP
DISLOCATIONS
GAS TURBINES
HARDENING
MATHEMATICAL MODELS
NICKEL BASE ALLOYS
PREDICTION EQUATIONS
SERVICE LIFE
STRESSES