Author: H. Eckstein
Publisher:
ISBN:
Category :
Languages : de
Pages : 18
Book Description
Preliminary results of a fracture mechanics model for iodine-induced crack growth in zircaloy-4 cladding tubes at 600 and 700Eckstein; P. Hofmann
Preliminary Results of a Fracture Mechanics Model for Iodine-induced Crack Growth in Zirkaloy-4 Cladding Tubes at 600° and 700°C
Preliminary Results of a Fracture Mechanics Model for Iodine-induced Crack Growth in Zircaloy 4 Cladding Tubes at 600 and 700 C
Preliminary Results of a Fracture Mechanics Model for Iodine-induced Crack Growth in Zircaloy 4 Cladding Tubes at 600 and 700 C
Preliminary results of a fracture mechanics model for iodine induced crack growth in zircaloy 4 cladding tubes at 600 and 700_347 C
Fracture Toughness of Hydrided Zircaloy-4 Sheet Under Through-Thickness Crack Growth Conditions
Author: P. A. Raynaud
Publisher:
ISBN:
Category : Acoustic emission
Languages : en
Pages : 16
Book Description
The susceptibility of fuel cladding to failure in the case of a postulated reactivity-initiated accident may be determined by crack initiation within a hydride blister or rim and subsequent crack growth through the thickness of the cladding. This study has determined the fracture toughness of hydrided cold-worked stress relieved Zircaloy-4 sheet subject to through-thickness crack growth at both 25 and 300°C. The experimental approach utilizes a novel procedure in which a narrow linear strip of brittle hydride blister across the specimen width creates a well-defined precrack upon initial loading. The subsequent crack growth resistance is then characterized by four-point bending of the specimen and an elastic-plastic fracture mechanics analysis. At room temperature, the through-thickness fracture toughness (Kq) is sensitive to the orientation of the hydride platelets and Kq?25 MPa?m for crack growth through a mixed in-plane/out-of-plane hydride field. In contrast, Kq is much nigher (?75 MPa?m) when the hydride platelets are oriented predominantly in the plane of the sheet and therefore normal to both the crack plane and the crack growth direction. At 300°C, the material exhibits greater ductility as the hydride particles within the matrix resist fracture such that Kq?83 MPa?m, despite the much lower flow stress of the material.
Publisher:
ISBN:
Category : Acoustic emission
Languages : en
Pages : 16
Book Description
The susceptibility of fuel cladding to failure in the case of a postulated reactivity-initiated accident may be determined by crack initiation within a hydride blister or rim and subsequent crack growth through the thickness of the cladding. This study has determined the fracture toughness of hydrided cold-worked stress relieved Zircaloy-4 sheet subject to through-thickness crack growth at both 25 and 300°C. The experimental approach utilizes a novel procedure in which a narrow linear strip of brittle hydride blister across the specimen width creates a well-defined precrack upon initial loading. The subsequent crack growth resistance is then characterized by four-point bending of the specimen and an elastic-plastic fracture mechanics analysis. At room temperature, the through-thickness fracture toughness (Kq) is sensitive to the orientation of the hydride platelets and Kq?25 MPa?m for crack growth through a mixed in-plane/out-of-plane hydride field. In contrast, Kq is much nigher (?75 MPa?m) when the hydride platelets are oriented predominantly in the plane of the sheet and therefore normal to both the crack plane and the crack growth direction. At 300°C, the material exhibits greater ductility as the hydride particles within the matrix resist fracture such that Kq?83 MPa?m, despite the much lower flow stress of the material.
Fracture Toughness and Crack Growth of Zerodur
Author: Michael J. Viens
Publisher:
ISBN:
Category : Ceramics
Languages : en
Pages : 34
Book Description
Publisher:
ISBN:
Category : Ceramics
Languages : en
Pages : 34
Book Description
Correlation of Failure Times for Iodine SCC of Zircaloy
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
A crack-growth model of stress corrosion cracking has been successfully applied to predict times-to-failure of zircaloy specimens exposed to iodine vapor. Data for two types of tests were analyzed using the model. The first was a variable loading experiment in which failure occurred after the specimen had been subjected to two distinct stresses in succession. The second was a series of tests in which surface roughness, and probably residual stress as well, was reduced by chemical polishing of the specimens. The success of the crack growth model in dealing with these situations suggests that crack propagation rather than crack initiation is the rate-controlling step in iodine stress corrosion cracking of zircaloy. Furthermore, the metal in the vicinity of the growing crack is apparently so embrittled by iodine that a model originally intended for ceramics applies.
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
A crack-growth model of stress corrosion cracking has been successfully applied to predict times-to-failure of zircaloy specimens exposed to iodine vapor. Data for two types of tests were analyzed using the model. The first was a variable loading experiment in which failure occurred after the specimen had been subjected to two distinct stresses in succession. The second was a series of tests in which surface roughness, and probably residual stress as well, was reduced by chemical polishing of the specimens. The success of the crack growth model in dealing with these situations suggests that crack propagation rather than crack initiation is the rate-controlling step in iodine stress corrosion cracking of zircaloy. Furthermore, the metal in the vicinity of the growing crack is apparently so embrittled by iodine that a model originally intended for ceramics applies.
Influence of Crystallographic Texture and Test Temperature on Initiation and Propagation of Iodine Stress-Corrosion Cracks in Zircaloy
Author: DB. Knorr
Publisher:
ISBN:
Category : Alloys
Languages : en
Pages : 26
Book Description
The effect of crystallographic texture on the initiation and the propagation of iodine stress-corrosion cracks in unirradiated Zircaloy is examined. Internal gas pressurization tests with iodine are performed on three tubing lots with different textures at 320 and 390°C. These smooth-bar tests yield data for time-to-failure and strain at failure versus hoop stress. Double-cantilever beam specimens provide crack velocity versus K and KISCC data at 300 to 310°C as a function of the texture ahead of the propagating crack. Smooth-bar threshold stress is strongly texture dependent over the temperature range 320 to 390°C. Basal poles oriented toward the direction of applied stress, such as a tangential tubing texture, result in faster crack propagation, lower KISCC, and a lower smooth-bar threshold stress. Plastic strain is shown to play an important role in crack intiation. The implication of texture and plastic strain effects on iodine SCC susceptibility of irradiated material is considered. Linear elastic fracture mechanics is found to be invalid for the short cracks observed in Zircaloy cladding.
Publisher:
ISBN:
Category : Alloys
Languages : en
Pages : 26
Book Description
The effect of crystallographic texture on the initiation and the propagation of iodine stress-corrosion cracks in unirradiated Zircaloy is examined. Internal gas pressurization tests with iodine are performed on three tubing lots with different textures at 320 and 390°C. These smooth-bar tests yield data for time-to-failure and strain at failure versus hoop stress. Double-cantilever beam specimens provide crack velocity versus K and KISCC data at 300 to 310°C as a function of the texture ahead of the propagating crack. Smooth-bar threshold stress is strongly texture dependent over the temperature range 320 to 390°C. Basal poles oriented toward the direction of applied stress, such as a tangential tubing texture, result in faster crack propagation, lower KISCC, and a lower smooth-bar threshold stress. Plastic strain is shown to play an important role in crack intiation. The implication of texture and plastic strain effects on iodine SCC susceptibility of irradiated material is considered. Linear elastic fracture mechanics is found to be invalid for the short cracks observed in Zircaloy cladding.
Linear Elastic Fracture Mechanics-based Simulation of Fatigue Crack Growth Under Non-proportional Mixed-mode Loading
Author: Ying Yang
Publisher:
ISBN: 9783939195399
Category :
Languages : en
Pages : 126
Book Description
Publisher:
ISBN: 9783939195399
Category :
Languages : en
Pages : 126
Book Description