The Effect of Hydrogen and Hydrides on the Integrity of Zirconium Alloy Components: Delayed Hydride Cracking (Engineering Materials)

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. front-matter 1 The Effect of Hydrogenand Hydrides on theIntegrity of ZirconiumAlloy Components 2 Preface 5 Acknowledgments 7 Contents 9 List of Abbreviations and Acronyms 14 Nomenclature 16 fulltext 30 1 Introduction 30 1.1...Overview 30 1.2...Delayed Hydride Cracking 32 1.3...Objectives and Outline 33 fulltext_001 35 2 Properties of Bulk Zirconium Hydrides 35 2.1...Hydride Phase Compositions, Lattice Structure and Parameter Determinations 35 2.1.1 Crystallographic Properties of the gamma -Hydride Phase 36 2.1.2 Phase Relationships, Phase Stability, and Hydrogen Compositions in the delta - and gamma -Hydride Phases at the ( alpha + delta )/ delta Phase Boundary 38 2.1.3 Crystallography of the delta -Hydride Phase 47 2.2...Mechanical Properties of Bulk Zirconium Hydrides 50 2.2.1 Yield Strength 50 2.2.2 Fracture Toughness 65 2.2.3 Microhardness, Elastic Moduli, Internal Friction 68 2.2.4 Summary of Mechanical Strength Results 77 References 79 fulltext_002 81 3 Hydride Phases, Orientation Relationships, Habit Planes, and Morphologies 81 3.1...Introduction 81 3.2...Hydride Precipitation in alpha -Zr Alloys: Early Analyses Derived from Observations of gamma -Hydride Precipitates 82 3.3...Hydride Precipitation in alpha --Zr Alloys: Determinations of Lattice Transformation Relationships of gamma -Hydride Precipitates 92 3.3.1 Introduction 92 3.3.2 \varvec\rm\{ 1\;0\;\overline{ 1} \;\boldell\} Habit Planes 94 3.3.3 \varvec\rm\{ 1\;0\;\overline{ 1} \;0\} Habit Planes 98 3.4...Hydride Precipitation in alpha / beta -Zr Alloys 102 3.5...Hydride Nucleation Studies in alpha / beta Zr-2.5Nb Pressure Tube Material 119 3.5.1 Microstructure of Zr-2.5Nb Alloys 119 3.5.2 Hydride Precipitation in alpha / beta Zr Microstructures 122 3.5.3 Hydride Precipitation in alpha / beta / omega Microstructures 123 3.5.4 Influence of Prior Deformation on Hydride Precipitation 127 References 133 fulltext_003 136 4 Solubility of Hydrogen 136 4.1...Solubility in the Dilute Phase of Single Phase Metal--Hydrogen Systems 136 4.2...Solubility of Hydrogen in the Dilute Phase of alpha / beta Zirconium Alloys 140 4.3...Effect of Stress on Hydrogen Chemical Potential in the Dilute Phase 143 4.4...Interaction Energy Expressions 150 4.4.1 Partial Molar Volume 150 4.4.2 Size--Effect Interaction 154 4.4.3 Diaelastic Polarizability 156 4.4.4 Paraelastic Polarizability 158 4.4.5 Interactions Between Hydrogen Atoms in Solution 159 4.5...Interaction of Hydrogen Atoms in Solution with Internal Defects 165 4.5.1 Density of Site Energies (DOSE) and Fermi--Dirac Statistics 166 4.5.2 Interaction of Hydrogen with Dislocations: DOSE Method 169 4.5.3 Formation of Hydrides at Dislocations: Thermodynamic Method 175 fulltext_004 180 5 Diffusion of Hydrogen 180 5.1...Phenomenological Flux Equations 180 5.2...Diffusivity---Theory 185 5.3...Diffusivity in Dilute Phase---Results 189 5.4...Thermal Diffusion---Results 199 References 200 fulltext_005 202 6 Characteristics of the Solvus 202 6.1...Introduction 202 6.2...General Considerations Concerning Hysteresis in Phase Transformations 204 6.3...Theories of Solvus Hysteresis Based on Accommodation Energy 216 fulltext_006 233 7 Theories of Coherent Phase Equilibrium 233 7.1...General Features 233 7.2...Polymorphic Phase Transformation 236 7.3...Isomorphic Phase Transformation 245 7.4...Stability Conditions and Path Dependences for Coherent Phase Transformations 255 7.4.1 Stability Conditions for Closed Polymorphic Systems 256 7.4.2 Stability Conditions for Open Isomorphic Systems 261 References 267 fulltext_007 269 8 Experimental Results and Theoretical Interpretations of Solvus Relationships in the Zr--H System 269 8.1...Introduction 269 8.2...Application of Coherent Phase Stability Analysis to the Zr--H System 270 8.3...Evaluation of Models of Hysteresis for the Zr--H System 275 8.4...Summary of Results of Experimental Solvus Determinations 279 8.4.1 Effect of Experimental Methods 280 8.4.2 Differences Between Solvi in alpha and alpha / beta Zr Materials: Effect of beta -Zr Phase 295 8.4.3 Effect of Cold Work and Irradiation 298 8.4.4 Combined Effect of Thermal Aging and Irradiation in Zr--2.5Nb 304 8.4.5 Effect of Manufacturing Variables, Microstructure, and/or Composition 307 References 312 fulltext_008 316 9 Fracture Strength of Embedded Hydride Precipitates in Zirconium and its Alloys 316 9.1...Introduction 316 9.2...Early Work 317 9.3...Fracture Strength of Radial Hydrides: Rising Load Tensile Tests 319 9.4...Mechanism for Fracture of Embedded Radial Hydride Clusters in Rising Load Tests 321 9.5...Hydride Stress State Determinations in Tensile Tests Observed Under Synchrotron X-ray Irradiation 330 9.6...Fracture Strength of Radial Hydrides: Constant Load Tests 343 9.7...Comparison of Rising Load and Constant Load Hydride Fracture Strength Results 351 References 353 fulltext_009 357 10 Delayed Hydride Cracking: Theory and Experiment 357 10.1...Introduction 357 10.2...Historical Overview 358 10.3...General Features of DHC 360 10.4...Theory of DHC Growth Rate 370 10.4.1 Test Temperature Approached from Below 378 10.4.2 Test Temperature Approached from Above 378 10.4.3 Dependence on Direction of Approach to Temperature 379 10.4.4 Dependence on K_{I} and Activation Energy 379 10.4.5 Dependence on Yield Strength 380 10.4.6 Dependence on Total Hydrogen Content 381 10.5...General Theory of K_{IH} 382 10.5.1 Introduction 382 10.5.2 Fracture Condition of Crack Tip Hydrided Region: K_{I} Versus L_{c} Relationship 382 10.5.3 Limiting Values of L_{c} and K_{IH} 386 10.5.4 K_{I} Versus L_{c} Relationship: Characteristics and Comparison with Experimental Data 393 10.5.5 Comparison of K_{I} Versus L_{c} Relationships from Different Models 397 10.5.5.1 Coupled Finite Element Models 397 10.5.5.2 Other Models of K_{IH} Giving Closed-Form Solutions 403 10.5.6 Limits to Crack Tip Hydrided Region Growth 404 10.5.7 Summary of General Limiting Conditions for DHC Initiation at Cracks 405 10.6...Analysis of Some Limiting Conditions for DHC 407 10.6.1 Introduction 407 10.6.2 High Temperature DHC Limit: Experimental Results 408 10.6.3 High Temperature DHC Limit: Theoretical Analysis 409 10.6.3.1 Unirradiated Material 409 10.6.3.2 Pre-Irradiated Material 413 10.6.4 DHC Arrest Temperature: Test Temperature Approached from Below 418 10.6.5 DHC Limiting Conditions: Summary Discussion and Conclusions 425 References 427 fulltext_010 433 11 DHC Initiation at Volumetric Flaws 433 11.1...Introduction 433 11.2...Early Models of Blunt Flaw Assessment 434 11.3...Hydride Process Zone Approach to Volumetric Flaw Assessment: General Considerations 436 11.4...Hydride Process Zone Model: Closed Form Solution 442 11.5...Hydride Process Zone Model: Effect of Flaw Tip Plasticity 445 11.6...Engineering Process Zone Model 448 11.7...Validation of the Engineering Process Zone Model 452 11.7.1 Flaw Shape 452 11.7.2 Flaw Root Radius 452 11.7.3 Flaws with Depth Greater than 1 mm 452 11.7.4 Flaw Surface Roughness and Secondary Flaw Significance 453 11.7.5 Use of Flaw Tip Plasticity and Creep in the Engineering Process Zone Model Application 455 11.7.6 Accuracy of the Cubic Polynomial Expression in the Engineering Process Zone Model Application 455 11.7.7 Scatter and Material Variability 456 11.7.8 Hydrogen Isotope Content and Number of Reactor Cooldown/Heatup Cycles 456 11.7.9 Above Threshold Conditions 457 11.7.10 Effect of Irradiation 457 11.7.11 Cyclic Loading and Overload Conditions 458 References 458 fulltext_011 460 12 Applications to CANDU Reactors 460 12.1...Introduction 460 12.2...Overview of Assessment Approach 462 12.2.1 DHC Initiation at Planar Flaws: K_{IH} 462 12.2.2 DHC Initiation at Volumetric Flaws: TSSD 464 12.2.3 Planar Flaw Growth to the End of an Assessment Period: DHC Growth Rate 466 12.2.4 Reactor Core Assessment: Leak Before Break Analysis 468 References 473 Annotation 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 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 focus 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 that our understanding of DHC is supported by progress across a broad range of fields. These include hysteresis associated with first-order phase transformations; phase relationships in coherent crystalline metallic solids; 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 Front Matter....Pages i-xxxii Introduction....Pages 1-5 Properties of Bulk Zirconium Hydrides....Pages 7-52 Hydride Phases, Orientation Relationships, Habit Planes, and Morphologies....Pages 53-107 Solubility of Hydrogen....Pages 109-152 Diffusion of Hydrogen....Pages 153-174 Characteristics of the Solvus....Pages 175-205 Theories of Coherent Phase Equilibrium....Pages 207-242 Experimental Results and Theoretical Interpretations of Solvus Relationships in the Zr–H System....Pages 243-289 Fracture Strength of Embedded Hydride Precipitates in Zirconium and its Alloys....Pages 291-331 Delayed Hydride Cracking: Theory and Experiment....Pages 333-408 DHC Initiation at Volumetric Flaws....Pages 409-435 Applications to CANDU Reactors....Pages 437-451