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Long-Term Thermal Stability of Alloy 825 as a High-Level Nuclear Waste Container Material

Published online by Cambridge University Press:  15 February 2011

D. S. Dunn
Affiliation:
Center for Nuclear Waste Regulatory AnalysesSouthwest Research Institute6220 Culebra Road, San Antonio, TX 78238-5166
Y.-M. Pan
Affiliation:
Center for Nuclear Waste Regulatory AnalysesSouthwest Research Institute6220 Culebra Road, San Antonio, TX 78238-5166
G. A. Cragnolino
Affiliation:
Center for Nuclear Waste Regulatory AnalysesSouthwest Research Institute6220 Culebra Road, San Antonio, TX 78238-5166
N. Sridhar
Affiliation:
Center for Nuclear Waste Regulatory AnalysesSouthwest Research Institute6220 Culebra Road, San Antonio, TX 78238-5166
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Abstract

The thermal exposure of Fe-Cr-Ni-Mo materials to certain temperature regimes often results in the formation of grain boundary carbides and the associated depletion of alloying elements. This phenomenon, termed sensitization, is frequently the result of welding processes or in service exposure to elevated temperatures. In this investigation, alloy 825, a candidate high-level nuclear waste (HLW) container material, was thermally exposed to temperatures in the range of 550 to 800 °C for periods of up to 1,000 hr. Sensitization of the material was evaluated by corrosion tests and grain boundary analyses using an analytical electron microscope. The sensitized microstructure was found to contain M23C6-type carbides as well as a Cr-depleted region in the vicinity of the grain boundaries. The degree of sensitization was correlated to the extent of Cr depletion in the grain boundary region.

Type
Research Article
Copyright
Copyright © Materials Research Society 1996

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