Brittle fracture induced by hydrides in zircaloy-4

Journal Article · Thu Oct 31 23:00:00 EST 1991 · Scripta Metallurgica; (United States)

DOI:https://doi.org/10.1016/0956-716X(91)90068-C· OSTI ID:5722722

Bai, J B; Francois, D; Prioul, C ^[1]; Lansiart, S ^[2]

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1. Lab. MSS/MAT CNRS URA 850, Ecole Centrale Paris, 92295 Chatenay Malabry Cedex (FR)
2. CEA/DTA/CEREM/DTM/SRMA, C.E. Saclay, 91191 Gif-sur-Yvette Cedex (FR)

Zircaloy-4 is used as a cladding material in the nuclear industry for fuel elements. Its mechanical properties can be drastically affected by the presence of hydrides, which form when hydrogen content exceeds the terminal solid solubility. This change often manifests itself as a reduction in ductility (elongation and reduction in area), coupled with the evolution of the fracture mode from ductile microvoid nucleation and coalescence to intergranular fracture. It has been found, at room temperature, that Zircaloy-4 undergoes a ductile to brittle transition when the hydrogen content (hydride volume fraction) in the specimen is higher than some critical value depending on the microstructure and the hydride morphology. Heat treatment of the material can shift the transition end point from 1050 ppm wt H for the stress-relieved state to 100-150 ppm wt H for the {beta} treated state, thus strongly suggesting that there may be some relationship between the microstructure (grain size and shape) and the ductile-brittle transition. It has also been reported that for the same hydriding condition, the hydrogen absorption rate is higher for the stress-relieved and recrystallized states and lower for the {beta} treated state. This phenomenon is very important for engineering applications because it is related to the determination of the safe life. Insufficient attention has been drawn to the quantitative evaluation and the modelization of the influence of the microstructure on the ductile-brittle transition in hydrided Zircaloy-4, though there has been some general research on the boundary structural effect on intergranular fracture. The present authors attempt to modelize this influence by an upper-limit model using the results of image analysis on the microstructures and tensile tests on hydrided sheet specimens.

• OSTI ID: 5722722
• Journal Information: Scripta Metallurgica; (United States), Journal Name: Scripta Metallurgica; (United States) Vol. 25:11; ISSN 0036-9748; ISSN SCRMB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102 -- Metals & Alloys-- Structure & Phase Studies
360103* -- Metals & Alloys-- Mechanical Properties
ALLOY-ZR98SN-4
ALLOYS
CHROMIUM ADDITIONS
CHROMIUM ALLOYS
CLADDING
CORROSION RESISTANT ALLOYS
CRYSTAL STRUCTURE
DEPOSITION
DUCTILITY
ELEMENTS
EMBRITTLEMENT
FUEL ELEMENTS
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
HEAT TREATMENTS
HYDRIDES
HYDROGEN
HYDROGEN COMPOUNDS
INDUSTRY
INHIBITION
IRON ADDITIONS
IRON ALLOYS
MATERIALS
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
MICROSTRUCTURE
NONMETALS
NUCLEAR INDUSTRY
QUANTITY RATIO
REACTOR COMPONENTS
SOLUBILITY
SURFACE COATING
TEMPERATURE RANGE
TEMPERATURE RANGE 0273-0400 K
TENSILE PROPERTIES
TIN ALLOYS
ZIRCALOY
ZIRCALOY 4
ZIRCONIUM ALLOYS
ZIRCONIUM BASE ALLOYS