Texture and stress state dependent creep in Zircaloy-2
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G. E. LUCAS is Assistant Professor of Nuclear Engineering, Department of Chemical and Nuclear Engineering, University of California, Santa Barbara, Santa Barbara, CA 93106. R. M. N. PELLOUX is Professor of Metallurgy, Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139. Manuscript submitted August 15, 1980. METALLURGICAL TRANSACTIONS A
However, there has been considerably less experimental characterization of creep anisotropy 8 and less still of strength-differential behavior in the creep regime? This is to some degree ironic in that creep is the predominant mode of inelastic deformation in nuclear core components: moreover, the deformation modes may be significantly different at high and low strain rates. 6 Consequently, a systematic study was undertaken to investigate the characteristics of the creep strengthdifferential and creep anisotropy in Zircaloy in a well-defined parametric regime. Specifically, creep behavior in textured Zircaloy-2 plate was investigated as a function of plate direction, stress, stress state, temperature and cold work. In addition, stress relaxation tests were performed at selected conditions to substantiate observations of creep characteristics.
MATERIALS Specimens used in this program were taken from 1.30 cm thick, cold-rolled Zircaloy-2 plate supplied by Teledyne Wah Chang Albany. This plate thickness was chosen as a compromise; it was necessary to have material thick enough that mechanical test specimens could be machined from the three principal directions, yet thin enough that texture variations through the thickness of the plate would not be excessive. The plate was fabricated by heating a 10.2 cm thick, beta-quenched slab to 900 ~ and rolling it to 3.3 cm; following a reheat to 800 ~ and quenching, the slab was heated to 350 ~ and rolled to 1.30 cm. Subsequent to final rolling, the plate was divided into two lots, one lot receiving a final stress-relief, vacuum anneal for four hours at 495 ~ and the other lot receiving a final vacuum anneal to the fully recrystallized condition for two hours at 565 ~ These two schedules were designated JA and JB, respectively; and henceforth the materials will be referred to by these designations.
ISSN 0360-2133/81/0713-1321500.75/0 9 1981 AMERICAN SOCIETY FOR METALS AND THE METALLURGICAL SOCIETY OF AIME
VOLUME 12A, JULY 1981--1321
LONGITUDINAL
TRANSVERSE DIRECTION
(a) LONGITUDINAL
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texture that anisotropic deformation could be observed. To characterize the texture, pole figures were generated by the method of Schulz. ~~Representative (0002) pole figures obtained in the rolling plane of the JA and JB plate at half-thickness are shown in Fig. 1. As can be seen, the (0002) textures of the JA and JB plates are quite similar, with basal poles lying in the normaltransverse plane and clustered about directions +_45 deg from the normal direction. This is analogous to commercial cladding texture, in which basal poles lie in the radial-circumferential plane 15 to 35 deg fr
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