Slow-bend Testing of Hydrided Zirconium

Abstract

THE embrittlement of zirconium by hydrogen is generally reflected by a decrease in the energy absorbed in fracture in an impact test, with a notched or unnotched specimen. Only in certain circumstances is a simultaneous reduction in ductility observed in a tensile test, and therefore the embrittlement has generally been considered attributable to high strain rates. However, some recent work we have carried out indicates that it is the actual mode of stressing—by bending—rather than the strain rate which promotes brittle fracture of hydrided zirconium in an impact test. Afterwards, slow-bend tests, both notched and unnotched, have proved useful in elucidating several of the factors which contribute to brittle fracture of zirconium. The relative unimportance of strain rate has been demonstrated by the occurrence of a brittle crack in a notched slow-bend test in which the bending to promote fracture took 48 h.