Effect of direction of approach of test temperature on fracture toughness of Zr–2.5Nb pressure tube material

Influence of loading rate and hydrogen content on fracture toughness of Zr-2.5Nb pressure tube material

“…As can be seen from Fig. 16 the maximum shear stress is observed in the ligament joining the two hydride plates [10]. Singh et al [10] have cited three factors as governing the HE of hydride Zr-alloys i.e.…”

“…To explain the difference in fracture toughness between heating and cooling tests, Singh et al [10] recently computed the stress fields between two diagonal hydrides using FEM. As can be seen from Fig.…”

“…16 the maximum shear stress is observed in the ligament joining the two hydride plates [10]. Singh et al [10] have cited three factors as governing the HE of hydride Zr-alloys i.e. : hydride volume fraction at the test temperature, stress field in the matrix and hydride and localised deformation between axial splits.…”

“…: hydride volume fraction at the test temperature, stress field in the matrix and hydride and localised deformation between axial splits. The localised deformation between axial splits dictates the fracture toughness of the hydride Zr-alloy [10]. For a given test temperature, the number of axial splits increased with an increase in pulling rate and resulted in more localised deformation between axial splits leading to a greater drop in fracture toughness due to the presence of hydrides.…”

“…There is no data available in literature showing the effect of loading rate on the fracture toughness of the Zr-2.5Nb pressure tube material. A greater concern is the effect of the loading rate on the fracture toughness of hydrided pressure tube materials because they show typical S curve behaviour with a lower shelf energy level one fourth of the un-hydrided material [9,10] furthermore, the loading rate may shift S curve into higher temperatures. This may lead to lower CCL at operating temperature or an increase in safe temperatures at which pressure tubes can be kept in pressurised conditions during reactor shut down.…”