Temperature increase of Zircaloy-4 cladding tubes due to plastic heat dissipation during tensile tests at 0.1–10 s−1 strain rates

This study is focused on the impact of rapid Reactivity Initiated Accident (RIA) representative strain rates (about 1 s−1 NEA, 2010) on the behavior and fracture of unirradiated cold work stress relieved Zircaloy-4 cladding tubes. Uniaxial ring tests (HT) and plane strain ring tensile tests (PST) were performed in the 0.1-10 s−1 strain rate range, at 25 °C. The local temperature increase due to plastic dissipation was measured with a high-speed infrared camera. Limited temperature increases were measured at 0.1 s−1 strain rate. Limited but not strongly localized temperature increases were measured at 1 s−1. Large temperature increase were measured at 5 and 10 s−1 (142 °C at 5 s−1 strain rate in HT tests). The local temperature increase induced heterogeneous temperature fields, which enhanced strain localization and resulted in a reduction of the plastic elongation at fracture.