Evaluation of SCC crack behavior in zirconium and zircaloy-2 using nonlinear fracture mechanics parameters |
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Authors: | M Nagai S Shimada S Nishimura H Ueda G Yagawa |
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Affiliation: | Nippon Nuclear Fuel Development Co., Ltd., 2163 Narita-machi, Oarai-machi, Higashi-ibaraki-gun, Ibaraki-ken, 311-13 Japan;Toshiba Corp., 8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa-ken, 235 Japan;University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113 Japan |
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Abstract: | Applicability of nonlinear fracture mechanics parameters, i.e. J-integral, crack tip opening displacement (CTOD), and crack tip opening angle (CTOA), to evaluation of stress corrosion crack (SCC) propagation rate was investigated using fully annealed zirconium plates and Zircaloy-2 tubing, both of which produce SCC with comparatively large plastic strain in an iodine environment at high temperatures.Tensile SCC tests were carried out at 300°C for center-notched zirconium plates and internal gas pressurization SCC tests at 350°C, for Zircaloy-2 tubing, to measure the SCC crack propagation rate. The J-integral around semi-elliptical SCC cracks produced in Zircaloy-2 tubing was calculated by a three-dimensional finite element method (FEM) code.The test results revealed that the SCC crack propagation rate dc/dt could be expressed as a function of the J-integral, which is the most frequently used parameter in nonlinear fracture mechanics, by the equation dc/dt = C · Jn, where C and n were experimental constants.Among the other parameters, CTOD and CTOA, the latter appeared to be useful for assessing the crack propagation rate, because it had a tendency to hold a constant value at various crack depths. |
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