Effect of Irradiation at 130, 650, and 775°F on Tensile Properties of Zircaloy-4 at 70, 650, and 775°F

TEM investigations have been performed on irradiated samples after deformation covering various testing conditions for different recrystallized Zr alloys. It is shown that for transverse tensile tests and internal pressure tests performed at 350°C, only basal channels are observed for strain levels up to uniform elongation, whereas only prismatic and pyramidal channels are observed for axial tensile test. Then, focusing on internal pressure testing, irradiation hardening and strain hardening behavior have been analyzed in detail and compared to TEM observations. It is proposed that dislocation channeling phenomenon leads to high strain incompatibility between channels and surrounding grains and therefore to high microscopic internal stresses. These high microscopic internal stresses are believed to induce strong kinematic hardening at the macroscopic scale, as suggested by the mechanical behavior analysis. Finally, a micro-mechanical model based on microscopic deformation mechanisms and using homogenization techniques is proposed, taking into account the observed channeling phenomenon.

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“…As reported by many authors [3,[23][24][25], it is shown that irradiation leads to a strong increase in flow stress. It can be noticed on Fig.…”

Section: Resultsmentioning

confidence: 62%

Plastic Deformation of Irradiated Zirconium Alloys: TEM Investigations and Micro-Mechanical Modeling

Onimus

Béchade

Prioul

et al. 2005

Journal of ASTM International

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“…The change in the microstructure of Zircaloy-4 affects its mechanical behavior compared to the behavior of Zircaloy-4 under non-irradiated conditions. According to previous studies made on the change in the mechanical properties caused by neutron irradiation (Baroch, 1975;Higgy and Hammad, 1972;Rieger and Lee, 1974;Yasuda et al, 1987), neutron irradiation increases the strength and hardness, and decreases the ductility, as illustrated in Fig. 5, showing the influence of neutron irradiation on the strength and ductility for Zircaloy-4 irradiated at low temperature (<373 K) and tensile-tested at room temperature (Higgy and Hammad, 1972).…”

Section: Tensile Propertiesmentioning

confidence: 60%