Effect of heat treatment at 1150 C on creep-rupture properties of alloy FA-180
- Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.
The alloy FA-180, with a composition of Fe-28Al-5Cr-0.5Nb-0.8Mo-0.025Zr-0.05C-0.005B (at.%), is of interest because of its improved creep-rupture resistance when compared to alloy FA-129 (Fe-28Al-5Cr-0.5Nb-0.2C). At a temperature of 593 C and under a stress of 207 MPa, the creep-rupture life of FA-129 heat treated for 1 h at 750 C is about 20 h while the FA-180 alloy lasts approximately 100 h. Heat treatment at 1,150 C has been shown to further improve the creep life of FA-180 and creep-rupture lives of approximately 2,000 h have been attained. This strengthening was attributed to the presence of fine matrix and grain boundary Zr-rich MC precipitates that were produced by the heat treatment. The current study continues the investigation of the effect of heat treatment at 1,150 C on the improvement of creep-rupture life in alloy FA-180. As part of the effort to understand the strengthening mechanisms involved with heat treatment at 1,150 C, transmission electron microscopy was used to correlate the microstructure with the improved creep resistance. Results indicate that heat treatment at 1,150 C for 1 h, followed by rapid quenching in water or mineral oil, produces even further improvements in the creep-rupture life of this alloy. A specimen being tested at 593 C and 207 MPa was stopped after over 6000 h of life, while another specimen lasted over 1,600 h at 650 C and 241 MPa. The microstructure of the oil-quenched specimen contained many dislocation loops which were not present in the air-cooled specimens. These loops pinned dislocations during creep testing at temperatures of 593--700 C, resulting in stabilized deformation microstructure and increased creep-rupture strength.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC05-96OR22464
- OSTI ID:
- 266754
- Report Number(s):
- CONF-9605167-9; ON: DE96012338; TRN: AHC29616%%151
- Resource Relation:
- Conference: 10. annual conference on fossil energy materials, Knoxville, TN (United States), 14-16 May 1996; Other Information: PBD: [1996]
- Country of Publication:
- United States
- Language:
- English
Similar Records
Effects of composition and heat treatment at 1150{degrees}C on creep-rupture properties of Fe{sub 3}Al-based alloys
Effects of composition and heat treatment at 1150{degrees}C on creep-rupture properties of Fe{sub 3}Al-based alloys
Related Subjects
IRON BASE ALLOYS
MICROSTRUCTURE
MECHANICAL PROPERTIES
HEAT TREATMENTS
ALUMINIUM ALLOYS
CHROMIUM ALLOYS
NIOBIUM ADDITIONS
MOLYBDENUM ADDITIONS
ZIRCONIUM ADDITIONS
TEMPERATURE RANGE 1000-4000 K
COMPARATIVE EVALUATIONS
TEMPERATURE RANGE 0400-1000 K
CREEP
RUPTURES
FRACTURE PROPERTIES
EXPERIMENTAL DATA
MECHANICAL TESTS