skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: ENABLING THE PRACTICAL APPLICATION OF OXIDE DISPERSION-STRENGTHENED FERRITIC STEELS

Abstract

Effort has continued to evaluate joints made in oxide dispersion-strengthened (ODS) FeCrAl by (i) pulsed plasma-assisted diffusion (PPAD) bonding, and (ii) transient liquid phase (TLP) bonding. Creep tests of PPAD-bonded butt joints in air at 1000 C, using small, shoulder-loaded, dog bone-shaped specimens and an incrementally-loaded test technique, indicated that failure occurred at loads of up to 82% of that required to fail the parent alloy in the same test. For high creep-strength ferritic steels joined by conventional welding methods, strength reduction factors of 50-80% are considered to be acceptable. The failures apparently did not initiate along the joints; the observed mode of failure of the joined specimens was the same as observed for monolithic specimens of this alloy, by crack-initiated transgranular brittle fracture, followed by ductile overload failure. The progress of TLP bonding has been slower, with the major effort focused on understanding the behavior of the transient liquid phase and its interaction with the alloy microstructure during the various stages of bonding. Creep testing using the same procedures also has been used to evaluate changes resulting from torsional deformation of ODS-FeCrAl tubes in an attempt to modify their microstructures and increase their hoop strength. Interpretation of the resultsmore » so far has not shown a clear trend, largely due to difficulties in measuring the effective angle of twist in the specimen gauge lengths. Other issues that have been addressed are the refinement of an approach for prediction of the oxidation-limited service lifetime of alumina scale-forming ODS alloys, and alternative routes for ODS alloy powder processing. Analysis of alloy specimens oxidized to failure (in some cases involving exposures for many thousands of hours) over a range of temperatures has provided an improved basis for calculating the values of parameters required in the lifing model (minimum Al content for protective behavior; initiation point for scale spallation); a quantitative description of the influence of specimen shape remains to be addressed.« less

Authors:
 [1];  [1];  [2];  [3];  [1]
  1. ORNL
  2. MER Corp., Tucson, AZ
  3. Consultant
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
FE USDOE - Office of Fossil Energy (FE)
OSTI Identifier:
936042
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: 21ST ANNUAL CONFERENCE ON FOSSIL ENERGY MATERIALS, Knoxville, TN, USA, 20070430, 20070502
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALLOYS; BONDING; CREEP; DEFORMATION; DIFFUSION; FERRITIC STEELS; LIFETIME; MICROSTRUCTURE; OXIDES; PROCESSING; SHAPE; SPALLATION; TESTING; TRANSIENTS; WELDING; ODS alloys; joining; creep strength; oxidation lifetime

Citation Formats

Wright, Ian G, Pint, Bruce A, Dyadko, Dr. Eugene G., Bornstein, Norman S., and Tatlock, Gordon J. ENABLING THE PRACTICAL APPLICATION OF OXIDE DISPERSION-STRENGTHENED FERRITIC STEELS. United States: N. p., 2007. Web.
Wright, Ian G, Pint, Bruce A, Dyadko, Dr. Eugene G., Bornstein, Norman S., & Tatlock, Gordon J. ENABLING THE PRACTICAL APPLICATION OF OXIDE DISPERSION-STRENGTHENED FERRITIC STEELS. United States.
Wright, Ian G, Pint, Bruce A, Dyadko, Dr. Eugene G., Bornstein, Norman S., and Tatlock, Gordon J. Mon . "ENABLING THE PRACTICAL APPLICATION OF OXIDE DISPERSION-STRENGTHENED FERRITIC STEELS". United States. doi:.
@article{osti_936042,
title = {ENABLING THE PRACTICAL APPLICATION OF OXIDE DISPERSION-STRENGTHENED FERRITIC STEELS},
author = {Wright, Ian G and Pint, Bruce A and Dyadko, Dr. Eugene G. and Bornstein, Norman S. and Tatlock, Gordon J},
abstractNote = {Effort has continued to evaluate joints made in oxide dispersion-strengthened (ODS) FeCrAl by (i) pulsed plasma-assisted diffusion (PPAD) bonding, and (ii) transient liquid phase (TLP) bonding. Creep tests of PPAD-bonded butt joints in air at 1000 C, using small, shoulder-loaded, dog bone-shaped specimens and an incrementally-loaded test technique, indicated that failure occurred at loads of up to 82% of that required to fail the parent alloy in the same test. For high creep-strength ferritic steels joined by conventional welding methods, strength reduction factors of 50-80% are considered to be acceptable. The failures apparently did not initiate along the joints; the observed mode of failure of the joined specimens was the same as observed for monolithic specimens of this alloy, by crack-initiated transgranular brittle fracture, followed by ductile overload failure. The progress of TLP bonding has been slower, with the major effort focused on understanding the behavior of the transient liquid phase and its interaction with the alloy microstructure during the various stages of bonding. Creep testing using the same procedures also has been used to evaluate changes resulting from torsional deformation of ODS-FeCrAl tubes in an attempt to modify their microstructures and increase their hoop strength. Interpretation of the results so far has not shown a clear trend, largely due to difficulties in measuring the effective angle of twist in the specimen gauge lengths. Other issues that have been addressed are the refinement of an approach for prediction of the oxidation-limited service lifetime of alumina scale-forming ODS alloys, and alternative routes for ODS alloy powder processing. Analysis of alloy specimens oxidized to failure (in some cases involving exposures for many thousands of hours) over a range of temperatures has provided an improved basis for calculating the values of parameters required in the lifing model (minimum Al content for protective behavior; initiation point for scale spallation); a quantitative description of the influence of specimen shape remains to be addressed.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}

Conference:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this conference proceeding.

Save / Share:
  • No abstract prepared.
  • An innovative gas atomization reaction synthesis technique was employed as a viable method to dramatically lower the processing cost for precursor oxide dispersion forming ferritic stainless steel powders (i.e., Fe-Cr-(Hf,Ti)-Y). During this rapid solidification process the atomized powders were enveloped by a nano-metric Cr-enriched metastable oxide film. Elevated temperature heat treatment was used to dissociate this metastable oxide phase through oxygen exchange reactions with Y-(Hf,Ti) enriched intermetallic compound precipitates. These solid state reactions resulted in the formation of highly stable nano-metric mixed oxide dispersoids (i.e., Y-Ti-O or Y-Hf-O) throughout the alloy microstructure. Subsequent high temperature (1200 C) heat treatments weremore » used to elucidate the thermal stability of each nano-metric oxide dispersoid phase. Transmission electron microscopy coupled with X-ray diffraction was used to evaluate phase evolution within the alloy microstructure.« less
  • High burnup capability of sodium cooled fast breeder reactor (SFR) fuels depends significantly on irradiation performance of their component materials. Japan Atomic Energy Agency (JAEA) has been developing oxide dispersion strengthened (ODS) ferritic steels and a precipitation hardened (PH) ferritic steel as the most prospective materials for fuel pin cladding and duct tubes, respectively. Technology for small-scale manufacturing is already established, and several hundreds of ODS steel cladding tubes and dozens of PH steel duct tubes were successfully produced. We will step forward to develop manufacturing technology for mass production to supply these steels for future SFR fuels. Mechanical propertiesmore » of the products were examined by out-of-pile and in-pile tests including material irradiation tests in the experimental fast reactor JOYO and foreign fast reactors. The material strength standards (MSSs) were tentatively compiled in 2005 for ODS steels and in 1993 for PH steel. In order to upgrade the MSSs and to demonstrate high burnup capability of the materials, we will perform a series of irradiation tests in BOR-60 and JOYO until 2015 and contribute to design study for a demonstration SFR of which operation is expected after 2025. (authors)« less
  • An oxide dispersion strengthened (ODS) ferritic steel with high temperature strength has been developed in line with low activation criteria for application in fusion power systems. The composition Fe-13.5Cr-2W-0.5Ti-0.25Y{sub 2}O{sup 3} was chosen to provide a minimum chromium content to insure fully delta-ferrite stability. High temperature strength has been demonstrated by measuring creep response of the ODS alloy in uniaxial tension at 650 and 900 C in an inert atmosphere chamber. Results of tests at 900 C demonstrate that this alloy has creep properties similar to other alloys of similar design and can be considered for use in high temperaturemore » fusion power system designs. The alloy selection process, materials production, microstructural evaluation and creep testing are described.« less