| Title |
Hydride Formation Characteristics and Mechanical Properties of Zircaloy-4 Cladding Tubes Produced by Various Manufacturers |
| Authors |
송재숙(Jae Sook Song) ; 김상동(Sang Dong Kim) ; 홍순익(Sun Ig Hong) ; 최용(Yong Choi) ; 김재원(Jae Won Kim) |
| Abstract |
Hydride formation behavior and its effect on the mechanical properties of Zircaloy-4 nuclear cladding tubing produced by various manufacturers were studied. The hydride was formed by high temperature cathodic hydrogen charging method(HCM). TEM works revealed that the grain size of the commercial Zircaloy-4 cladding tubes was 2-7㎛ in which Zr(Fe, Cr)₂ was uniformly precipitated. δ(ZrH) spectra was mainly observed in the alloy after HCM, and, ZrH₂ and ZrO_(0.35) phases were hardly observed by X-ray analysis. The hydride was found to significantly influence the mechanical properties such as ductility, ultimate tensile strength, yield strength, the crack initiation and propagation behavior. The strain rate sensitivity and the activation volume of the cladding tubes containing the hydrides were observed to be not much different from those without hydrides, suggesting the deformation mechanism before crack initiation is not greatly influenced by the presence of hydrides. The rate controlling mechanism of the deformation was well explained by the dislocation trough model in which the segregation of alloying elements on dislocation determines the activation length. |