Introduction To The Characterization Of Residual Stress By Neutron Diffraction

by Hutchings; M.T.

• ISBN13: 9780415310000
• ISBN10: 0415310008
• Edition: 1st
• Format: Hardcover
• Copyright: 2005-02-28
• Publisher: CRC Press

Summary

Over the past 25 years the field of neutron diffraction for residual stress characterization has grown tremendously, and has matured from the stage of trial demonstrations to provide a practical tool with widespread applications in materials science and engineering. While the literature on the subject has grown commensurately, it has also remained fragmented and scattered across various journals and conference proceedings.For the first time, this volume presents a comprehensive introduction to stress measurement using neutron diffraction. It discusses all aspects of the technique, from the basic physics, the different neutron sources and instrumentation, to the various strategies for lattice strain measurement and data interpretation. These are illustrated by practical examples. This book represents a coherent unified treatment of the subject, written by well-known experts. It will prepare students, engineers, and other newcomers for their first neutron diffraction experiments and provide experts with a definitive reference work.

Table of Contents

Introduction	1	(24)
Residual Stress: Friend or Foe?	1	(1)
Historical Development of Stress Measurement by Diffraction	2	(4)
Laboratory X-Ray Diffraction	3	(2)
Synchrotron X-Ray Diffraction	5	(1)
Neutron Diffraction	5	(1)
Special Characteristics of Neutron Strain Measurement	6	(4)
Nature and Origin of Residual Stress	10	(7)
Macrostresses and Microstresses	11	(3)
Measurement of Macrostresses and Microstresses	14	(1)
Diffraction Techniques	15	(1)
Other Measurement Techniques	16	(1)
Effects of Residual Stress	17	(8)
Static Loading	17	(1)
Fatigue Loading	18	(3)
References	21	(4)
Fundamentals of Neutron Diffraction	25	(40)
Introduction	25	(2)
Scattering and Absorption of Neutrons and X-Rays by Atoms	27	(7)
Neutron Scattering	27	(3)
Coherent Scattering Cross-Section	30	(1)
Incoherent Scattering Cross-Section	30	(1)
Absorption Cross-Section	31	(1)
Tabulation of Neutron Cross-Sections	32	(1)
X-Ray Scattering	32	(2)
Neutron Diffraction from Crystalline Solids	34	(21)
Crystal Lattice	35	(2)
Diffraction from Crystal Lattice Planes	37	(2)
Observation of Diffraction Peaks	39	(1)
Reciprocal Lattice Approach to Diffraction Theory	40	(1)
Reciprocal Lattice	40	(1)
Neutron Coherent Elastic Cross-Section	41	(5)
Lattice Plane Spacings	46	(1)
Orthogonal Crystal Structures	47	(1)
Hexagonal Structures	48	(1)
Lower Symmetry Structures	48	(1)
Diffracted Intensity	49	(3)
Scattering from Engineering Materials	52	(1)
Scattering from Elements	52	(1)
Scattering from Alloys	52	(1)
Application to Titanium Alloys	53	(1)
Macroscopic Cross-Section	53	(1)
Elements	53	(1)
Alloys	54	(1)
Penetration of Neutron Beams	55	(1)
Effects of Lattice Vibrations	56	(2)
Extinction, Texture, and Multiple Scattering	58	(7)
Extinction	58	(1)
Texture	59	(1)
Multiple Scattering	60	(3)
References	63	(2)
Diffraction Techniques and Instrument Design	65	(84)
Neutron Sources	65	(13)
Steady-State Reactor Neutron Source	66	(1)
Moderation	67	(2)
Neutron Guide Tubes	69	(4)
Neutron Lenses	73	(1)
Time-Pulsed Neutron Source	73	(4)
Safety	77	(1)
Diffractometers for Strain Measurement	78	(22)
Reactor-Based Continuous Beam Instrument for Strain Measurement	79	(1)
Basic Instrument	79	(4)
Instrument Construction	83	(1)
Monochromator and Choice of Wavelength	84	(4)
Collimation	88	(1)
Apertures and Beam Area Definition	89	(2)
Shielding	91	(1)
Time-Pulsed Beam Instrument for Strain Measurement	92	(1)
Time-Pulsed Neutron Beams on Reactors	92	(1)
Time-Pulsed Neutron Beams from Pulsed Sources	93	(3)
Instruments on a Spallation Source	96	(3)
Collimation	99	(1)
Neutron Detectors	100	(3)
Position-Sensitive Detectors and Detector Arrays	101	(2)
The Instrumental Resolution	103	(5)
Continuous Beam Instrument	104	(3)
Time-Pulsed Beam Instrument	107	(1)
Instrument Gauge Volumes	108	(6)
Instrument Reference Point	109	(1)
Gauge Volume	109	(1)
Nominal Gauge Volume	110	(1)
Instrumental Gauge Volume	111	(3)
Definition of Instrumental Gauge Volume When Using a Position-Sensitive Detector	114	(1)
Sampled Gauge Volume and Effective Measurement Position	114	(22)
Sampled Gauge Volume	114	(2)
Effects of Beam Attenuation in Sample	116	(3)
Geometric and Attenuation Shifts of Effective Centroid of Sampled Gauge Volume	119	(1)
Sample Positioning	120	(1)
Sample Positioning, Orientation, and Movement	120	(3)
Mounting the Sample	123	(3)
Anomalous Angular Shifts Due to Surface Effects	126	(5)
Corrections for Anomalous Angle Shifts	131	(3)
Minimizing Anomalous Angle Shifts	134	(2)
Specialized Instruments for Strain Measurement	136	(13)
Triple-Axis Spectrometer	136	(2)
Use of Horizontally Curved Silicon Crystals	138	(2)
Specialized Time-of-Flight Techniques	140	(2)
Transmission Techniques	142	(2)
References	144	(5)
Practical Aspects of Strain Measurement Using Neutron Diffraction	149	(54)
Introduction	149	(3)
Measurement of Diffraction Bragg Peak Profile	152	(5)
Choosing an Appropriate Gauge Volume	152	(1)
Choosing an Appropriate Reflection	153	(1)
Elastic Regime	154	(1)
Plastic Regime	154	(1)
Avoidance of Anomalous Shifts of Angle Due to Bragg Edges	155	(2)
Measurement of Many Peaks in a Diffraction Pattern	157	(1)
Scanning the Diffraction Peak	157	(1)
Analyzing Bragg Peak Profiles	157	(7)
Expressions for Peak Profiles	159	(1)
Symmetric Peaks from Continuous Source Diffractometers	159	(2)
Asymmetric Peaks from Time-Pulsed Source Instruments	161	(1)
Fitting a Profile to a Single Diffraction Peak	162	(2)
Accuracy of Diffraction Peak Center Determination	164	(18)
Accuracy of Fitted Parameters	164	(1)
Uncertainty in Case of Negligible Background	164	(2)
Effects of Background on Strain Uncertainty	166	(3)
Systematic Uncertainties	169	(1)
Time Required to Achieve a Given Accuracy in Peak Center Measurement	169	(1)
Measuring at Positions Deep within a Sample	170	(4)
Analytical and Empirical Studies of Scan Optimization	174	(1)
Range of Scan	174	(1)
Fitting a Sloping Background	175	(2)
Weighting	177	(1)
VAMAS Recommendations on Peak Fitting	178	(3)
Strategy of Peak Fitting	181	(1)
Sources of Background Counts	182	(1)
Analysis of Complete Diffraction Profiles for Strain	182	(1)
Strain-Free Reference	183	(14)
Requirement	183	(1)
Other Factors That Can Affect Lattice Spacing	184	(2)
Measurement of Reference d0-Spacing	186	(1)
Far-Field Reference	187	(1)
Powders, Cubes, and Combs	188	(4)
d0 Measurement Using X-Rays	192	(1)
d0 Measurement by Neutron Transmission	192	(4)
Imposing Stress Balance	196	(1)
Reproducibility Tests	197	(6)
Recording Measurement Details	199	(1)
References	199	(4)
Interpretation and Analysis of Lattice Strain Data	203	(60)
Inferring Stresses from Lattice Strains	203	(7)
Basic Continuum Relationship between Strain and Stress	203	(3)
Diffraction-Specific Elastic Constants	206	(1)
X-Ray Measurement of Stress	207	(3)
Introduction to Mechanics of Crystallite Deformation	210	(5)
Elastic Anisotropy of Single Crystals	215	(7)
Elastic Anisotropy of Cubic Single Crystals	216	(5)
Elastic Anisotropy of Hexagonal Crystals	221	(1)
The Bulk Elastic Response of Polycrystals	222	(5)
Voigt and Reuss Models for Macroscopic Bulk Properties	223	(1)
Voigt Model for Bulk Properties	223	(1)
Reuss Model for Bulk Properties	224	(1)
Kroner Model for Macroscopic Bulk Properties	225	(2)
hkl-Specific Response in a Polycrystal Undergoing Elastic Deformation	227	(3)
Voigt and Reuss Models	227	(1)
Voigt Model	227	(1)
Reuss Model	227	(1)
Kroner Model	228	(2)
hkl-Specific Response in a Polycrystal Undergoing Plastic Deformation	230	(24)
Elastoplastic Self-Consistent Models	233	(1)
Implementation of EPSC Model	234	(3)
Predicting Crystallographic Slip	237	(2)
EPSC Predictions of Lattice Strains under Plastic Straining	239	(3)
EPSC Predictions of Residual Intergranular Strains	242	(2)
Analysis of Experimental Data	244	(1)
Uniaxial Tensile Loading of Aluminum	244	(2)
Uniaxial Tensile Loading of Stainless Steel	246	(1)
Hexagonal Materials	246	(2)
Cyclical Loading	248	(1)
Rietveld Analysis of Diffraction Patterns	249	(4)
Summary	253	(1)
Analysis of Bragg Peak Broadening	254	(9)
References	257	(6)
Applications to Problems in Materials Science and Engineering	263	(84)
Introduction	263	(2)
Welded Structures	265	(24)
Origin and Nature of Weld Stresses	266	(2)
Comparison of Various Stress Measurement Techniques	268	(6)
Challenges to Accurate Neutron Diffraction Measurement of Weldment Stresses	274	(4)
Examples of Stress Measurement in Weldments	278	(1)
Alumino-Thermic Welds	278	(1)
Manual Metal Arc Repair Welds	279	(2)
Electron Beam Welds	281	(1)
Friction-Based Welds	281	(6)
Future Directions for Neutron Diffraction Studies of Weldments	287	(1)
Validation of Finite Element Models	287	(1)
Postweld Heat Treatment	288	(1)
Phase Transformations	288	(1)
Strategies for Improved Lifetime	289	(1)
Composites and Other Multiphase Materials	289	(27)
Nature and Origins	289	(2)
Mean Phase-Specific Microstresses	291	(1)
Methods for Measurement of Stress in Composites	291	(1)
Raman Spectroscopy	291	(1)
Photoelasticity	291	(1)
Diffraction Techniques	292	(7)
Separation of Different Stress Contributions in Composites	299	(2)
Elastic Mismatch Stresses	301	(2)
Thermal Microstresses	303	(3)
Particulate Composites	306	(1)
Whisker Composites	307	(2)
Continuous Fiber Composites	309	(1)
Plastic Misfit Stresses	309	(1)
Continuous Fiber Metal Matrix Systems	310	(1)
Phase Transformation Stresses	311	(1)
Microstress-Related Peak Broadening	312	(2)
Future Directions for Neutron Diffraction Measurements of Composites	314	(2)
Plastically Deformed Components and Materials	316	(8)
Origin and Nature of Plastic Misfit Stresses	316	(1)
Challenges to Accurate Neutron Diffraction Measurement of Stress in Plastically Deformed Components	316	(1)
Examples of Stress Measurement in Plastically Deformed Materials	317	(1)
Studies of Fundamental Aspects of Material Deformation	317	(1)
Practical Example of Intergranular Stresses: Bent Monel Tube	318	(2)
Stress in a Highly Textured Sample	320	(2)
Intergranular Lattice Strain as an Indicator of Macroscopic Plastic Strain	322	(2)
Future Directions for Neutron Diffraction Measurement of Stress in Plastically Deformed Components	324	(1)
Near-Surface Stresses	324	(9)
Origin and Nature of Near-Surface Stresses	325	(1)
Challenges to Accurate Neutron Diffraction Measurement of Stress Near Surfaces	325	(3)
Examples of Measurement of Stress Near Surfaces	328	(1)
Machining Stresses	328	(1)
Shot-Peening	329	(1)
Carburized Layers	330	(2)
Future Directions for Neutron Diffraction Measurement of Stress Near Surfaces	332	(1)
In Situ and Through-Process or Life Studies	333	(14)
Manufacturing Process Studies	334	(2)
Heat Treatment	336	(2)
Service Life Studies	338	(2)
References	340	(7)
The Future	347	(2)
Symbols and Abbreviations	349	(8)
Glossary	357	(4)
Appendix 1 Note on Reactor Flux Spectrum	361	(4)
Appendix 2 Relation between the Centroid of Sampled Gauge Volume and Translator Reading	365	(4)
Appendix 3 Points for Consideration When Making a Neutron Diffraction Stress Measurement	369	(10)
Appendix 4 Macroscopic Scattering Cross-Sections of All Elements	379	(6)
Index	385