High temperature low cycle fatigue and correlation to crack growth rate in two nickel-base superalloys
Thesis/Dissertation
·
OSTI ID:5246238
Low-cycle fatigue of two advanced nickel-base superalloys, PM/HIP Astroloy and PM/HIP Rene '95, was studied at 650/sup 0/C and 725/sup 0/C. These alloys are potential candidate materials for aircraft turbine disk applications. The main purpose of this study was to determine the relative importance of creep and oxidation that might occur at high temperature. Fully reversed strain controlled tests were performed at a frequency of 0.33 Hz in high purity argon. Creep was simulated by superposition of 2 or 5 min hold times at the maximum tensile strain. Microstructural features, fracture characteristics and dislocation structures were examined by phase separation, SEM, EDAX, and TEM techniques. The nature of the crack tip deformation also was examined by AES. Employing a tensile hold was more damaging than raising temperature. Raising temperature from 650/sup 0/C to 725/sub 0/C did not change the transgranular crack propagation mode, whereas employing hold times caused mixed transgranular (TG) + intergranular (IG) propagation. Crack initiation was also changed to IG by employing a tensile hole which was otherwise TG. In Rene '95 pores were the major crack initiation site, while in Astroloy second phase particles, such as borides and grain boundary ..gamma..', were observed at the origin.
- Research Organization:
- Rensselaer Polytechnic Inst., Troy, NY (USA)
- OSTI ID:
- 5246238
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
ALLOYS
ALUMINIUM ALLOYS
ASTROLOY
BORON ADDITIONS
BORON ALLOYS
CARBON ADDITIONS
CHEMICAL REACTIONS
CHROMIUM ALLOYS
COBALT ALLOYS
CRACKS
CREEP
FATIGUE
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
HIGH TEMPERATURE
MATERIALS
MECHANICAL PROPERTIES
MOLYBDENUM ALLOYS
NICKEL ALLOYS
NICKEL BASE ALLOYS
NIOBIUM ALLOYS
OXIDATION
RENE 95
THERMAL FATIGUE
TITANIUM ALLOYS
TUNGSTEN ALLOYS
ZIRCONIUM ADDITIONS
ZIRCONIUM ALLOYS
360103* -- Metals & Alloys-- Mechanical Properties
ALLOYS
ALUMINIUM ALLOYS
ASTROLOY
BORON ADDITIONS
BORON ALLOYS
CARBON ADDITIONS
CHEMICAL REACTIONS
CHROMIUM ALLOYS
COBALT ALLOYS
CRACKS
CREEP
FATIGUE
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
HIGH TEMPERATURE
MATERIALS
MECHANICAL PROPERTIES
MOLYBDENUM ALLOYS
NICKEL ALLOYS
NICKEL BASE ALLOYS
NIOBIUM ALLOYS
OXIDATION
RENE 95
THERMAL FATIGUE
TITANIUM ALLOYS
TUNGSTEN ALLOYS
ZIRCONIUM ADDITIONS
ZIRCONIUM ALLOYS