Download or read book Effect of Hydrogen on Mechanical Behavior of a Zircaloy 4 Alloy written by and published by . This book was released on 2005 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydride formation is one of the main degradation mechanisms of zirconium alloys in hydrogen-rich environments. When sufficient hydrogen is present, zirconium- hydride precipitates can be formed. Cracking of the brittle hydrides near a crack tip can initiate the growth of a crack leading to the premature failure of the material. Hydride formation is believed to be enhanced by the presence of residual or applied stresses. Therefore, the increase in the stress field ahead of a crack tip may promote precipitation of additional hydrides. In order to verify these phenomena, the effect of internal stresses on the zirconium-hydride-precipitate formation, and in turn, the influence of the hydrides on the subsequest intergranular strain evolution in a hexagonal-close-packed zircaloy-4 alloy were investigated, using neutron and x-ray diffraction. First, the evolution of intergranular strains in a zircaloy-4 was investigated in-situ, using neutron diffraction, to understand the deformation behavior at the microscopic length scale. A series of uniaxial tensile loads up to 500 MPa was applied to a round-bar tensile specimen in the as-received condition and the intergranular (hkl-specific) strains, parallel and perpendicular to the loading direction, were studied. The results provide a fundamental understanding of the anisotropic elastic-plastic deformation of the zirconium alloy under applied stresses. Then the hydride formation was examined by conducting qualitative phase mapping across the diameter of two tensile specimens charged with hydrogen gas for 1/2 hour and 1 hour, respectively. It was observed that the zirconium hydrides ([delta]-ZrH2) form a layer, in a ring shape, near the surface with a thickness of approximately 400 [mu]m. The hydrogen-charging effects on intergranular strains were investigated and compared to the as-received specimen. Second, spatially-resolved internal-strain mapping was performed on a fatigue pre-cracked compact-tension (CT) specimen using in-situ neutron diffraction under applied loads of 667 and d4,444 newtons, to determine the in-plane (parallel to the loading direction) and through-thickness (perpendicular to the loading direction) lattice-strain profiles around the crack tip. An increase in elastic lattice strains near the crack tip was observed with the increase in the applied stresses. The effect of hydrogen charging was also investigated on CT specimens electrochemically charged with hydrogen. X-ray diffraction results clearly showed the presence of zircomium hydrides on the surfaces of the specimen.

Download or read book The Effect of Hydrogen and Hydrides on the Integrity of Zirconium Alloy Components written by Manfred P. Puls and published by Springer Science & Business Media. This book was released on 2012-08-04 with total page 475 pages. Available in PDF, EPUB and Kindle. Book excerpt: By drawing together the current theoretical and experimental understanding of the phenomena of delayed hydride cracking (DHC) in zirconium alloys, The Effect of Hydrogen and Hydrides on the Integrity of Zirconium Alloy Components: Delayed Hydride Cracking provides a detailed explanation focusing on the properties of hydrogen and hydrides in these alloys. Whilst the emphasis lies on zirconium alloys, the combination of both the empirical and mechanistic approaches creates a solid understanding that can also be applied to other hydride forming metals. This up-to-date reference focuses on documented research surrounding DHC, including current methodologies for design and assessment of the results of periodic in-service inspections of pressure tubes in nuclear reactors. Emphasis is placed on showing how our understanding of DHC is supported by progress in general understanding of such broad fields as the study of hysteresis associated with first order phase transformations, phase relationships in coherent crystalline metallic solids, the physics of point and line defects, diffusion of substitutional and interstitial atoms in crystalline solids, and continuum fracture and solid mechanics. Furthermore, an account of current methodologies is given illustrating how such understanding of hydrogen, hydrides and DHC in zirconium alloys underpins these methodologies for assessments of real life cases in the Canadian nuclear industry. The all-encompassing approach makes The Effect of Hydrogen and Hydrides on the Integrity of Zirconium Alloy Component: Delayed Hydride Cracking an ideal reference source for students, researchers and industry professionals alike.

Download or read book Hydrogen Content Preoxidation and Cooling Scenario Effects on Post Quench Microstructure and Mechanical Properties of Zircaloy 4 and M5 Alloys in LOCA Conditions written by J. -C. Brachet and published by . This book was released on 2008 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: Previous papers pointed out the influence of long-term service exposures on the thermal-mechanical behavior of Zr alloys in LOCA conditions and, especially, the impact of in-service hydrogen pick-up on post-quench mechanical properties. Moreover, the oxide layer grown under in-service conditions was occasionally expected to have a protective effect against high temperature oxidation. Finally, the oxygen and hydrogen distributions within the prior-? layer appear as a key parameter with regard to the residual ductility of the alloy, especially as a function of the cooling scenario. The objective of the study presented here was to further investigate the influence of these parameters on the post-quench mechanical properties. Unirradiated Zircaloy-4 and M5® cladding tubes were consequently hydrided up to different concentration levels, then oxidized at high temperature (1000-1200°C) up to at least 10 % measured equivalent cladding reacted (ECR) and directly quenched to room temperature (RT). Ring compression tests (RCT), 3-point bending tests (3PBT) at RT and 135°C, as well as impact tests at RT were then performed to determine the evolution of the post-quench mechanical properties of Zircaloy-4 and M5® alloys with H content. Similarly, specimens preoxidized out-of-pile were also submitted to high temperature oxidation and direct quench, as well as to post-quench ring compression tests. Along with calculations of oxygen diffusion in the metal, results from those tests allowed us to estimate the assumed protective effect of the pretransient oxide layer. Finally, using specimens in the as-received condition or hydrided to typical end-of-life H contents, the effect of temperature history after oxidation at 1200°C was studied, i.e., at the end of the high temperature isothermal oxidation, samples were either submitted to direct quenching to RT or to slow cooling to different final quenching temperatures. It was thus demonstrated that the cooling scenario has a significant impact on the post-quench mechanical properties. All test samples were investigated by means of fractographic examinations to assess the type of failure mode. Moreover, a deep metallurgical analysis has been performed: SEM and image analysis were used for accurate phase thickness measurements, nuclear and electron microprobes for quantitative mapping of hydrogen and oxygen. It proved that the oxygen and hydrogen contents and their distribution in the prior-? layer have a first-order influence on the residual ductility. From all the results obtained on as-received and hydrided samples directly quenched from the oxidation temperature, it was then possible to derive a relationship between structural parameters, i.e., oxygen and hydrogen contents and thickness of the prior-? layer, and the post-quench impact properties at RT.

Download or read book Zirconium in the Nuclear Industry written by Gerry D. Moan and published by ASTM International. This book was released on 2002 with total page 891 pages. Available in PDF, EPUB and Kindle. Book excerpt: Annotation The 41 papers of this proceedings volume were first presented at the 13th symposium on Zirconium in the Nuclear Industry held in Annecy, France in June of 2001. Many of the papers are devoted to material related issues, corrosion and hydriding behavior, in-reactor studies, and the behavior and properties of Zr alloys used in storing spent fuel. Some papers report on studies of second phase particles, irradiation creep and growth, and material performance during loss of coolant and reactivity initiated accidents. Annotation copyrighted by Book News, Inc., Portland, OR.

Download or read book Effect of Hydrogen on Mechanical Properties of Zirconium and Its Tin Alloys written by G. T. Muehlenkamp and published by . This book was released on 1953 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mechanical Properties of Zircaloy 2 written by R. L. Mehan and published by . This book was released on 1961 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Review of Zircaloy 2 and Zircaloy 4 Properties Relevant to N S Savannah Reactor Design written by C. L. Whitmarsh and published by . This book was released on 1962 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Effect of Hydrogen on the Deformation Behavior of Zircaloy 4 written by Michelle E. Flanagan and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fundamental Deformation Micromechanics in a Zircaloy 4 Alloy and the Hydrogen Effects on Its Microstructure Internal Stresses and Fatigue Behavior written by Elena Garlea and published by . This book was released on 2008 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: Zircaloy-4 alloys, polycrystalline zirconium alloys, are extensively used in the nuclear industry. During the service in the reactor, these alloys absorb hydrogen, leading to formation of zirconium hydrides, which may be enhanced by the stress field around a crack tip. In order to investigate these phenomena in a Zircaloy-4 alloy, the effect of internal stresses on the hydride precipitation and the subsequent influence on the fatigue behavior has been studied. Firstly, the deformation systems responsible for the polycrystalline plasticity at the grain level, in a hexagonal-close-packed, coarse-grained, and random-textured Zircaloy-4 alloy are considered. The evolution of internal strains was measured in-situ, using neutron diffraction, during uniaxial tensile loading up to 7% strain. The macroscopic stress-strain curve and the intergranular (hkil-specific) strain development, parallel and perpendicular to the loading direction, are measured. Then, a new elastoplastic self-consistent (EPSC) modeling scheme is employed to simulate the experimental results. The model shows a good agreement with the measured data. Secondly, the hydride phase formation and its influence on fatigue crack growth in Zircaloy-4 alloy are investigated. The microstructure and fatigue behavior of the Zircaloy alloy in the as-received condition is shown. Then, the formation and distribution of hydride phase in the alloy, and its effect on microstructure and the fatigue crack propagation rates is discussed. The residual lattice strain profile ahead of a fatigue crack has been also measured using neutron diffraction. The combined effect of residual strain and hydride precipitation on the fatigue behavior is presented and discussed. In addition, the zirconium lattice strains evolution under applied loads of 900, 1,800, and 2,700 N in the presence of hydrides is studied, and compared with the as-received condition. Finally, we report the experimental results from neutron incoherent scattering and neutron radiography studies on hydrogen charged Zircaloy-4 specimens. Future work is planned to study the kinetics of hydride formation under applied load, using neutron diffraction and in-situ hydrogen charging.

Download or read book Hydrogen Effects in Materials written by Anthony W. Thompson and published by John Wiley & Sons. This book was released on 2013-09-27 with total page 1090 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the Fifth International Conference on the Effect of Hydrogen on the Behavior of Materials sponsored by the Structural Materials Division (SMD) Mechanical Metallurgy and Corrosion & Environmental Effects Committees of The Minerals, Metals & Materials Society held at Jackson Lake Lodge, Moran, Wyoming, September 11-14, 1994.

Download or read book The Effects of Hydrogen on the Mechanical Properties and Fracture of Zr and Refractory Metals written by H. K. Birnbaum and published by . This book was released on 1973 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect of hydrogen on the mechanical properties of zirconium and the refractory metals is reviewed with particular attention to the effects on fracture and ductility. The various mechanisms proposed for the hydrogen embrittlement of these metals is reviewed. Both the effects of hydrogen in solution and in the surrounding gas phase is considered. New results on the embrittlement of Nb and Nb-N alloys obtained using a variety of experimental techniques is presented and discussed relative to the generic embrittlement phenomena in these metals. The relation of the crack propagation mechanism to stress and temperature induced phase changes is discussed and a model of hydrogen embrittlement is put forth. (Modified author abstract).

Download or read book Mechanical Behavior at High Temperatures of Highly Oxygen Or Hydrogen Enriched and Prior Phases of Zirconium Alloys written by Isabelle Turque and published by . This book was released on 2018 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt: During a hypothetical loss-of-coolant accident, zirconium alloy fuel claddings can be loaded by internal pressure and exposed to steam at high temperatures (HTs) up to 1,200°C and then cooled and quenched in water. A significant fraction of the oxygen that reacts with the cladding during HT oxidation diffuses beneath the oxide through the metallic substrate. This induces a progressive transformation of the metallic ?Zr-phase layer into an intermediate layer of ?Zr(O) phase containing up to 7 weight % (wt.%) oxygen. Furthermore, in some specific conditions, the cladding may rapidly absorb a significant amount of hydrogen during steam exposition at HTs. As a ?Zr stabilizer, hydrogen would mainly diffuse and concentrate up to several thousands of parts per million by weight (wppm) into the inner ?Zr-phase layer. This study intends to provide new and more comprehensive data on the HT mechanical behavior of the ?Zr(O) and (prior-)?Zr phases containing high contents of oxygen and hydrogen, respectively. Model samples produced from M5® and Zircaloy-4 cladding tubes homogeneously charged in oxygen (less than or equal to 6 wt.%) and hydrogen (less than or equal to 3,000 wppm), respectively, were prepared. Their mechanical behavior was determined under vacuum between 800 and 1,100°C for the oxygen-enriched ?Zr phase and in air between 700 and 20°C after cooling from the ?Zr temperature domain for the hydrogen-enriched (prior-)?Zr phase. The ?Zr phase was substantially strengthened and embrittled by oxygen. The contribution of the ?Zr(O) layer to the HT creep behavior of an oxidized fuel cladding tube subjected to internal pressure is evaluated by finite element analysis. Mechanical strength and ductility of the model (prior-)?Zr phase appear to be affected by hydrogen contents of 2000-3000 wppm in ways that depend on temperature.

Download or read book Phase Transformations written by Srikumar Banerjee and published by Elsevier. This book was released on 2010-05-31 with total page 837 pages. Available in PDF, EPUB and Kindle. Book excerpt: The terms phase transitions and phase transformations are often used in an interchangeable manner in the metallurgical literature. In Phase Transformations, transformations driven by pressure changes, radiation and deformation and those occurring in nanoscale multilayers are brought to the fore. Order-disorder transformations, many of which constitute very good examples of continuous transformations, are dealt with in a comprehensive manner. Almost all types of phase transformations and reactions that are commonly encountered in inorganic materials are covered and the underlying thermodynamic, kinetic and crystallographic aspects elucidated. Shows readers the advancements in the field - due to enhanced computing power and superior experimental capability Drawing upon the background and the research experience of the authors, bringing together a wealth of experience Written essentially from a physical metallurgists view point

Download or read book Effect of Hydride Distribution on the Mechanical Properties of Zirconium Alloy Fuel Cladding and Guide Tubes written by Suresh K. Yagnik and published by . This book was released on 2014 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt: Localization of hydride precipitates exacerbates the hydrogen embrittlement effects on the deformation and fracture properties of Zircaloy fuel cladding materials. Thus, at comparable hydrogen concentration levels, localized hydride precipitates are more detrimental from the standpoint of cladding integrity during service. Indeed, the hydride precipitates are often non-homogeneously distributed in fuel assembly components; for example, in irradiated fuel cladding, the hydride rim is formed near the outer oxide-metal interface because of the temperature gradient that exists during operation. With increasing fuel burnup, this hydride rim not only becomes denser but might be accompanied by gradients in local hydrogen and hydride concentrations through the rest of the cladding wall thickness. Whereas the importance of hydride spacing and their orientation, as well as the alloy matrix ligaments interspaced with the distributed hydride has been recognized in the literature, little work has been reported on the effects of hydride precipitate distribution on the mechanical properties of Zircaloy fuel assembly component materials. In this paper, we report on an extensive mechanical test program on low-tin Zircaloy-4 specimens from stress-relieved cladding and recrystallized guide tubes, charged with hydrogen to obtain uniform, rimmed, and layered hydride distributions. The hydrogen concentration (0-1200 ppm) and hydride rim thickness (10-90 ?m) were also varied. The strain rate was kept at 10-4/s to simulate in-service steady-state conditions and the tests were conducted both at room temperature and 300°C. All test specimens were of small-gauge-section, cut-outs from cladding, and guide tubes. The loading configurations included slotted-arc test (SAT) on half-ring-shaped specimens and uniaxial tension test (UTT) on dog-bone-shaped cut-outs. Further, prompted by the finite-element analysis of the gauge-section region, a unique geometry of internal slotted-arc specimens with parallel gauge section (ISATP) was chosen. Detailed stress-strain curves for all tests were measured, and post-test fractography and local hydrogen concentrations within the gauge sections were measured by hot extractions. Comparative data on the measured strengths and elongations for the three types of hydride distributions (i.e., uniform, rimmed, and layered) are presented. Quantification and analyses of these effects have provided a general constitutive stress-strain relationship for assessing margins to cladding or guide tube failures.

Download or read book Hydrogen Migration and Mechanical Behavior of Hydrided Zirconium Alloys written by Soyoung Kang and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Zirconium alloys have been widely used for nuclear fuel cladding materials in light-water nuclear reactors. The cladding corrodes as a result of exposure to the coolant water and produces hydrogen as a result of the corrosion reaction. A fraction of this hydrogen can be picked up into the cladding material. Once the hydrogen content reaches the terminal solid solubility, zirconium hydride particles start to precipitate. The cladding suffers waterside corrosion in service, leading to hydrogen ingress, which can redistribute in the cladding and form hydrides. Because these zirconium hydrides are more brittle than the zirconium matrix, they can deteriorate the ductility of the cladding. Therefore, understanding hydrogen behavior in cladding is important to maintain cladding integrity. This study aims to investigate hydrogen migration under a temperature gradient and mechanical behavior of hydrided zirconium alloys. The hydrogen transport and hydride precipitation /dissolution model HNGD was implemented in the fuel performance code BISON to predict hydrogen behavior. The hydrogen is distributed inhomogeneously in the cladding as a result of Fick's law and Soret effect. The hydrogen tends to move from higher to lower concentration governed by Fick's law and higher to lower temperature based on the Soret effect. Hydrogen migration tests were designed to determine the heat of transport value (Q*) of hydrogen in Zr, a parameter needed to evaluate the Soret effect. Hydrided samples were subjected to a long annealing schedule in a temperature gradient to re-distribute the hydrogen. The annealed samples were cut into several pieces along the temperature gradient, and the hydrogen contents were analyzed using hot vacuum extraction. The hydrogen distribution along the temperature gradient was observed in this experiment, and from this data, the heat of transport value (Q*) was determined. Further, the mechanical behavior of zirconium alloys was assessed using ring compression tests. The zirconium alloy tubes were characterized by electron backscatter diffraction (EBSD) to identify the microstructure of materials. Stress relieved anneal ZIRLO (SRA) and low Sn Partially recrystallized anneal LT ZIRLO (PRXA) show different grain shapes and sizes. After characterization, the zirconium alloy tubes were hydrogen charged and cut into 8 mm length rings. The ring samples were subjected to compression at 12 o'clock following a specified thermomechanical cycle. This thermomechanical treatment caused partial precipitation of radial hydrides in certain positions of the ring samples. The radial hydride fractions were characterized and showed a difference between ZIRLO and LT ZIRLO because of their different microstructures. Finite element modeling conducted using ABAQUS could then determine the threshold stress for two materials by comparing simulation results (stress state) and hydride morphologies. In addition, the ring compression tests for assessing hydrided cladding ductility for various hydride morphologies were conducted at room temperature. Ring samples with different radial hydride continuity factors (RHCF) were tested to determine their load-displacement curves. The 1% permanent strain and 2 % offset strain criteria were chosen to assess the ductility of samples. The ductility degrades with increasing RHCF.

Download or read book Corrosion of Titanium written by J. D. Jackson and published by . This book was released on 1966 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mechanical Behaviour of Materials VI written by M. Jono and published by Elsevier. This book was released on 2013-10-22 with total page 3510 pages. Available in PDF, EPUB and Kindle. Book excerpt: Significant progress in the science and technology of the mechanical behaviour of materials has been made in recent years. The greatest strides forward have occurred in the field of advanced materials with high performance, such as ceramics, composite materials, and intermetallic compounds. The Sixth International Conference on Mechanical Behaviour of Materials (ICM-6), taking place in Kyoto, Japan, 29 July - 2 August 1991 addressed these issues. In commemorating the fortieth anniversary of the Japan Society of Materials Science, organised by the Foundation for Advancement of International Science and supported by the Science Council of Japan, the information provided in these proceedings reflects the international nature of the meeting. It provides a valuable account of recent developments and problems in the field of mechanical behaviour of materials.