Metal Failures

Preface xv 1. Failure Analysis 1 I. Introduction 1 II. Examples of Case Studies Involving Structural Failures 6 III. Summary 25 References 25 Problems 26 2. Elements of Elastic Deformation 27 I. Introduction 27 II. Stress 27 III. Strain 32 IV. Elastic Constitutive Relationships 35 V. State of Stress Ahead of a Notch 44 VI. Summary 46 References 46 Appendix 2-1: Mohr Circle Equations for a Plane Problem 46 Appendix 2-2: Three-Dimensional Stress Analysis 49 Appendix 2-3: Stress Formulas Under Simple Loading Conditions 54 Problems 57 3. Elements of Plastic Deformation 59 I. Introduction 59 II. Theoretical Shear Strength 59 III. Dislocations 61 IV. Yield Criteria for Multiaxial Stress 68 V. State of Stress in the Plastic Zone Ahead of a Notch in Plane-Strain Deformation 70 VI. Summary 74 For Further Reading 75 Appendix 3-1: The von Mises Yield Criterion 75 Problems 76 4. Elements of Fracture Mechanics 80 I. Introduction 80 II. Griffith’s Analysis of the Critical Stress for Brittle Fracture 80 III. Alternative Derivation of the Griffith Equation 83 IV. Orowan-Irwin Modification of the Griffith Equation 84 V. Stress Intensity Factors 85 VI. The Three Loading Modes 88 VII. Determination of the Plastic Zone Size 88 VIII. Effect of Thickness on Fracture Toughness 89 IX. The R-Curve 91 X. Short Crack Limitation 92 XI. Case Studies 92 XII. The Plane-Strain Crack Arrest Fracture Toughness, K I a, of Ferritic Steels 95 XIII. Elastic-plastic Fracture Mechanics 96 XIV. Failure Assessment Diagrams 98 XV. Summary 101 References 101 Problems 102 5. Alloys and Coatings 105 I. Introduction 105 II. Alloying Elements 106 III. Periodic Table 107 IV. Phase Diagrams 108 V. Coatings 126 VI. Summary 130 References 130 Problems 130 6. Examination and Reporting Procedures 132 I. Introduction 132 II. Tools for Examinations in the Field 132 III. Preparation of Fracture Surfaces for Examination 133 IV. Visual Examination 133 V. Case Study: Failure of a Steering Column Component 134 VI. Optical Examination 135 VII. Case Study: Failure of a Helicopter Tail Rotor 136 VIII. The Transmission Electron Microscope (TEM) 136 IX. The Scanning Electron Microscope (SEM) 138 X. Replicas 142 XI. Spectrographic and Other Types of Chemical Analysis 143 XII. Case Study: Failure of a Zinc Die Casting 144 XIII. Specialized Analytical Techniques 145 XIV. Stress Measurement by X-Rays 146 XV. Case Study: Residual Stress in a Train Wheel 149 XVI. The Technical Report 150 XVII. Record Keeping and Testimony 151 XVIII. Summary 154 References 155 Problem 155 7. Brittle and Ductile Fractures 156 I. Introduction 156 II. Brittle Fracture 156 III. Some Examples of Brittle Fracture in Steel 159 IV. Ductile-Brittle Behavior of Steel 161 V. Case Study: The Nuclear Pressure Vessel Design Code 168 VI. Case Study: Examination of Samples from the Royal Mail Ship (RMS) Titanic 172 VII. Ductile Fracture 177 VIII. Ductile Tensile Failure, Necking 177 IX. Fractographic Features Associated with Ductile Rupture 183 X. Failure in Torsion 185 XI. Case Study: Failure of a Helicopter Bolt 185 XII. Summary 188 References 191 Problems 191 8. Thermal and Residual Stresses 196 I. Introduction 196 II. Thermal Stresses, Thermal Strain, and Thermal Shock 196 III. Residual Stresses Caused by Nonuniform Plastic Deformation 200 IV. Residual Stresses Due to Quenching 204 V. Residual Stress Toughening 207 VI. Residual Stresses Resulting from Carburizing, Nitriding, and Induction Hardening 207 VII. Residual Stresses Developed in Welding 209 VIII. Measurement of Residual Stresses 211 IX. Summary 211 References 211 Appendix 8-1: Case Study of a Fracture Due to Thermal Stress 212 Problems 213 9. Creep 216 I. Introduction 216 II. Background 216 III. Characteristics of Creep 217 IV. Creep Parameters 220 V. Creep Fracture Mechanisms 222 VI. Fracture Mechanism Maps 224 VII. Case Studies 225 VIII. Residual Life Assessment 230 IX. Stress Relaxation 232 X. Elastic Follow-up 233 XI. Summary 234 References 234 Problems 234 10. Fatigue 237 I. Introduction 237 II. Background 237 III. Design Considerations 240 IV. Mechanisms of Fatigue 246 V. Factors Affecting Fatigue Crack Initiation 254 VI. Factors Affecting Fatigue Crack Growth 257 VII. Analysis of the Rate of Fatigue Crack Propagation 261 VIII. Fatigue Failure Analysis 273 IX. Case Studies 276 X. Thermal-Mechanical Fatigue 285 XI. Cavitation 285 XII. Composite Materials 286 XIII. Summary 287 References 287 For Further Reading 290 Problems 290 11. Statistical Distributions 293 I. Introduction 293 II. Distribution Functions 293 III. The Normal Distribution 294 IV. Statistics of Fatigue; Statistical Distributions 296 V. The Weibull Distribution 298 VI. The Gumbel Distribution 302 VII. The Staircase Method 307 VIII. Summary 310 References 310 Appendix 11-1: Method of Linear Least Squares (C. F. Gauss, 1794) 311 Problems 314 12. Defects 316 I. Introduction 316 II. Weld Defects 316 III. Case Study: Welding Defect 321 IV. Casting Defects 328 V. Case Study: Corner Cracking during Continuous Casting 329 VI. Forming Defects 329 VII. Case Studies: Forging Defects 330 VIII. Case Study: Counterfeit Part 332 IX. The Use of the Wrong Alloys; Errors in Heat Treatment, etc. 333 X. Summary 334 References 334 Problems 334 13. Environmental Effects 336 I. Introduction 336 II. Definitions 336 III. Fundamentals of Corrosion Processes 337 IV. Environmentally Assisted Cracking Processes 342 V. Case Studies 348 VI. Cracking in Oil and Gas Pipelines 350 VII. Crack Arrestors and Pipeline Reinforcement 352 VIII. Plating Problems 353 IX. Case Studies 353 X. Pitting Corrosion of Household Copper Tubing 356 XI. Problems with Hydrogen at Elevated Temperatures 356 XII. Hot Corrosion (Sulfidation) 358 XIII. Summary 358 References 358 Problems 359 14. Flaw Detection 360 I. Introduction 360 II. Inspectability 360 III. Visual Examination (VE) 364 IV. Penetrant Testing (PT) 364 V. Case Study: Sioux City DC-10 Aircraft 367 VI. Case Study: MD-88 Engine Failure 374 VII. Magnetic Particle Testing (MT) 375 VIII. Case Study: Failure of an Aircraft Crankshaft 378 IX. Eddy Current Testing (ET) 382 X. Case Study: Aloha Airlines 384 XI. Ultrasonic Testing (UT) 384 XII. Case Study: B747 389 XIII. Radiographic Testing (RT) 389 XIV. Acoustic Emission Testing (AET) 391 XV. Cost of Inspections 393 XVI. Summary 393 References 394 Problems 394 15. Wear 396 I. Wear 396 II. The Coefficient of Friction 397 III. The Archard Equation 398 IV. An Example of Adhesive Wear 399 V. Fretting Fatigue 399 VI. Case Study: Friction and Wear; Bushing Failure 403 VII. Roller Bearings 404 VIII. Case Study: Failure of a Railroad Car Axle 410 IX. Gear Failures 410 X. Summary 414 References 414 Problems 415 Concluding Remarks 417 Solutions to Problems 419 Name Index 469 Subject Index 473