Hydrogen influence on fracture mechanics characteristics of zirconium alloy Zr-2.5 Nb at ambient and elevated temperatures

Abstract

The main objective of the work – investigation of aging process of Ignalina NPP fuel channel tubes manufac-tured from zirconium alloy Zr-2,5 Nb, i.e. determination of the influence of hydrogen content and temperature on frac-ture toughness characteristics and critical integral J I C . The main factor initiating degradation of the fuel channel materials under operating conditions is hydrogen, which forms during corrosion process and is absorbed inzim alloy. In zirconium alloy containing with hydro-gen form hydrides, which cause brittlene ss of this alloy and decrease strength to brittle fracture. Fracture toughness characteristics QK, *CK and CJI were investigated on compact specimens (B ≈ 4 mm)hydrogen and containing with hydrogn , 100 ppm) at 20, 170, 200 and 300ºC. The investigation showed that characteristics of fracture toughness depended a little on hydrogen saturation value and more on temperature. The critiCIfor containing with hydrogen specimens decreases at 20ºC, however at the increase of test temperature to 300ºC also increases. Analysis of *CK and J1C dependence on mechanical characteristics of zirconium alloy has shown, that modifiedplasticity ()0,2modpmZ = satisfactory approximated the influence of temperature and hydrogen concentration on this characteristics variation.