Zr-2.5Nb alloy is used for the pressure tubes in CANDU reactors. Current as-manufactured tubes are produced in a cold-worked and stress-relieved metallurgical condition. The tubes installed in reactors normally operate at ∼300°C. In a hypothetical loss-of-coolant-accident (LOCA), the pressure tube may be overheated to 1000°C. During the temperature transient, a phase transformation occurs that changes the microstructure and affects the material's high-temperature deformation behaviour. In this study, improvements to enhance the performance of pressure-tube materials are being explored by modifying the texture and microstructure of as-manufactured pressure tubes. Two modifications were carried out by high-temperature annealing, with or without subsequent cold-working. This paper presents the resulting modified textures as measured by neutron diffraction and their texture evolution during heating. The anisotropy factors calculated for the modified Zr-2.5Nb pressure-tube materials using the measured texture data are compared with those previously characterized for Zircaloy-4 fuel cladding. The resulting effect of these texture and microstructure modifications with regard to the material's response to anisotropic deformation during heating to high temperatures is also discussed in this paper.

Additional Metadata
Conference 8th Pacific Rim International Congress on Advanced Materials and Processing 2013, PRICM 8
Citation
Fong, R. (Randy), Vogel, S. (Sven), Miller, R, & Saari, H. (2013). Characterization of the crystallographic textures and mechanical anisotropy factors in two modifications of Zr-2.5Nb pressure tube materials. In 8th Pacific Rim International Congress on Advanced Materials and Processing 2013, PRICM 8 (pp. 71–78).