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Evaluation of Ductility of Zircaloy-2 Materials Using a Small Ellipsoidal-Shaped Punch

Fong, RWL
Research Scientist and Technologist,Atomic Energy of Canada Ltd., Chalk River Laboratories,Ontario,

Fraser, CR
Research Scientist and Technologist,Atomic Energy of Canada Ltd., Chalk River Laboratories,Ontario,


Pages: 12    Published: Jan 1998


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Source: STP1329-EB


Abstract

Seam-welded Zircaloy-2 calandria tubes are used in the fuel channel of CANDU reactors, to isolate the hot pressure tube from the cool heavy-water moderator. The mechanical properties of irradiated welds are required to assess whether they will be satisfactory to the end-of-life of the reactor. It is impractical to irradiate short sections of calandria tube for burst testing. Therefore, we have developed a small ellipsoidal-shaped punch to evaluate the mechanical properties of anisotropic Zircaloy-2 material having various microstructures such as those present in a welded calandria tube. Small punch tests were performed on four different types of calandria tubes, two welded and two seamless, and the results show that the mechanical anisotropy of the tubes could be differentiated. The fracture produced in unirradiated small specimens showed a straight-line crack, similar to a straight-line rupture on a tube during burst testing. A re-constitution of the properties from small specimens was used for correlation with the burst properties of the tubes. A consistent correlation was obtained for the punch load and displacement with the burst strength and ductility of the tubes. Based on this correlation, mechanical properties of irradiated welds using the small ellipsoidal punch method are being evaluated.


Keywords:
weld, ductility, burst test, Zircaloy-2, nuclear materials, small punch test

Paper ID: STP38015S
Committee/Subcommittee: E10.02
DOI: 10.1520/STP38015S
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