Welding Deformation and Residual Stress Prevention

by Ma; Murakawa; Ueda

• ISBN13: 9780123948045
• ISBN10: 0123948045
• Format: Hardcover
• Copyright: 2012-03-12
• Publisher: Elsevier Science

Summary

Generally, welding produces welding deformation and residual stress in the products, which influences the quality and performance of the products. Although many engineers and researchers have made great effort how to control these incidents, they have still remained unresolved. Welding Deformation and Residual Stress Prevention provides a unique computational approach to the prediction of the effects of deformation and residual stress on materials. The goal is to provide engineers and designers with the ability to create their own computational system for predicting and possibly avoiding the problem altogether. The basic theories including "theory of elastic-plastic analysis" and "inherent strain theory" , and analysis procedures are described using a simple three-bar model. Online simulation software to perform basic analysis on welding mechanics Examples of strategic methods and procedures are illustrated to have solved various welding-related problems encountered in the process of construction. Appendices present data bases for welding residual stresses, temperature dependent material properties, etc.

Table of Contents

Preface	p. xi
List of Symbols	p. xv
Introduction to Welding Mechanics
Basic Concepts of Welding and Welding Mechanics	p. 1
Process of the Production of Residual Stress and Inherent Strain	p. 8
Illustrative Model	p. 8
Heating of Free Bar C	p. 12
Heating of Bar C Fixed at Both Ends	p. 13
Heating Bar C When It Is Connected to a Movable Rigid Body	p. 21
Reproduction of Residual Stress by Inherent Strain and Inverse Analysis for Inherent Strain	p. 27
Reproduction of Residual Stress by Inherent Strain	p. 27
Inverse Analysis for Inherent Strain	p. 28
Numerical Examples of Residual Stress, Inherent Strain, and Inherent Displacement	p. 29
Low-Temperature Heating Process	p. 30
Medium-Temperature Heating	p. 31
High-Temperature Heating	p. 33
References	p. 34
Introduction to Measurement and Prediction of Residual Stresses with the Help of Inherent Strains
Inherent Strains and Resulting Stresses	p. 36
Displacement-Strain Relation (Compatibility)	p. 38
Stress-Strain Relation (Constitution Equation)	p. 39
Equilibrium Condition (Equilibrium Equation)	p. 39
Measured Strains in Experiments and Inherent Strains	p. 40
Effective and Noneffective Inherent Strains	p. 41
Determination of Effective Inherent Strains from Measured Residual Stresses	p. 42
Most Probable Value of Effective Inherent Strain and Accuracy of the Measurement of Residual Stress	p. 45
Derivation of Elastic Response Matrix	p. 46
Measuring Methods and Procedures of Residual Stresses in Two- and Three-Dimensional Models	p. 48
Measurement of Two-Dimensional Residual Stresses Induced in the Butt-Welded Joint of a Plate	p. 48
Measurement of Three-Dimensional Residual Stresses Induced in Thick Plates	p. 49
Prediction of Welding Residual Stresses	p. 52
References	p. 52
Mechanical Simulation of Welding
Heat Flow and Temperature During Welding	p. 55
Heat Supply, Diffusion, and Dissipation	p. 56
Simple Heat Flow Model	p. 59
Differences in Material Properties	p. 63
Change of Material Properties with Temperature	p. 64
Characteristic Temperature and Length	p. 69
Simple Method for Solving the Heat Conduction Problem	p. 74
Summary	p. 79
Basic Concepts of Mechanical Problems in Welding	p. 79
Classification of Problems According to Dimensions	p. 80
Variables and Equations Used to Describe Mechanical Problems	p. 81
Deformation and Stress in the Three-Bar Model	p. 84
Stress-Strain Relation in Welding	p. 87
Thermal Visco-Elasto-Plastic Problem in Three-Bar Model	p. 94
Closing Remarks	p. 96
References	p. 97
The Finite Element Method
Finite Element Method as a Powerful Tool for a Variety of Problems	p. 99
Types of Problems and the Corresponding Basic Equations	p. 101
Basic Concepts of the Variational Principle	p. 103
How to Solve a Problem with More than One Element	p. 104
Equilibrium Equation of a Bar	p. 104
Equilibrium Equations of Two Bars	p. 105
Incremental Method for Nonlinear Problems	p. 108
Simple Examples of Analyzing Thermal Elastic-Plastic-Creep Behavior	p. 109
Bar Fixed at Both Ends Under a Thermal Cycle	p. 109
Thermal Elastic Behavior of a Bar Fixed at Both Ends	p. 112
Thermal Elastic-Plastic Behavior of a Bar Fixed at Both Ends	p. 113
Thermal Elastic-Plastic Creep Behavior of a Bar Fixed at Both Ends	p. 114
Basic Theoretical Solutions to Validate Results Obtained by the FEM	p. 115
Temperature Distribution Due to a Concentrated Heat Source	p. 115
Temperature Distribution on a Butt-Welded Joint of a Thin Plate	p. 116
Temperature Distribution on a Butt-Welded Joint of a Thick Plate	p. 119
Inherent Strain Distribution on a Butt-Welded Joint of a Thin Plate	p. 120
Flow of Analysis for Welding Deformation and Residual Stress	p. 122
Checklist for Rational Simulation	p. 124
Checklist for Preparation of Input Data	p. 124
Checklists for the Results of Simulation	p. 125
Troubleshooting for Problems Experienced in Computation	p. 126
Troubleshooting for Common Problems in Heat Conduction Analysis and Stress Analysis	p. 126
Troubleshooting for Heat Conduction Analysis	p. 126
Troubleshooting for Thermal Elastic-Plastic Analysis	p. 128
References	p. 129
Q&A for FEM Programs
Q&A for Program Introduction	p. 131
Q&A for Welding Heat Conduction Program heat2d.exe	p. 135
Q&A for Thermal Elastic-Plastic Creep Program tepc2d.exe	p. 140
Q&A for the Inherent Strain-Based Program inhs2d.exe	p. 142
Q&A for Postprocessing Program awsd.exe	p. 144
Q&A for Sample Data	p. 152
Reference	p. 167
Simulation Procedures for Welding Heat Conduction, Welding Deformation, and Residual Stresses Using the FEM Programs Provided on the Companion Website
Simulation Steps Using the Welding Heat Conduction FEM Program	p. 170
Purpose and Simulation Conditions	p. 170
Preparation of Input File	p. 171
Steps to Execute heat2d.exe for Welding Heat Conduction	p. 176
Viewing Results Using Postprocessing Program	p. 176
Simulation Steps Using the Thermal Elastic-Plastic Creep FEM Program	p. 178
Purpose and Simulation Conditions	p. 178
Preparation of Input File	p. 179
Prepare the Node Temperature File	p. 185
Steps to Execute the FEM Program	p. 185
Viewing Results Using the Postprocessing Program	p. 185
Simulation Steps Using the Inherent Strain FEM Program	p. 188
Purpose and Simulation Conditions	p. 188
Preparation of Input File	p. 189
Steps to Execute the Program	p. 192
Comparison of the Results of the Inherent Strain Method and the Thermal Elastic-Plastic Method	p. 192
Numerical Experiment for Residual Stress Measurement Using the Inherent Strain FEM Program	p. 193
Purpose and Simulation Conditions	p. 193
Preparation of Input File	p. 194
Steps to Execute the FEM Program for Residual Stress and Deformation	p. 199
Comparison of the Results of the Inherent Strain Method and the Thermal Elastic-Plastic Method	p. 199
Computation Steps for the Prediction of Residual Stresses by the Inherent Strain Method	p. 200
Purpose and Simulation Conditions	p. 200
Preparation of Input File and Prediction Formula of Inherent Strain	p. 200
Steps to Execute inhs2d.exe for Residual Stress Computation	p. 206
Comparison of the Results by the Inherent Strain Method and the Thermal Elastic-Plastic Method	p. 206
Reference	p. 207
Strategic Simulation Analyses for Manufacturing Problems Related to Welding
Cold Cracking at the First Pass of a Butt-Welded Joint Under Mechanical Restraint	p. 210
Cold Cracking of Slit Weld	p. 213
Analysis of Welding Residual Stress of Fillet Welds for Prevention of Fatigue Cracks	p. 216
Residual Stresses by Three-Dimensional Analysis	p. 216
Comparison of Residual Stresses by Two-Dimensional and Three-Dimensional Analyses	p. 216
Comparison of Residual Stresses in Single-Pass and Multipass Welds	p. 219
Multipass-Welded Corner Joints and Weld Cracking	p. 221
Experiment and Result	p. 221
Residual Stresses by Thermal Elastic-Plastic Analysis	p. 221
Effects of Welding Residual Stress and Geometry of Edge Preparation on Initiation of Welding Cracks	p. 223
Analysis of Transient and Residual Stresses of Multipass Welding of Thick Plates in Relation to Cold Cracks, Under-Bead Cracks, Etc.	p. 227
Specimens and Conditions for Theoretical Analysis	p. 227
Characteristics of Welding Residual Stress Distributions and Production Process	p. 230
Improvement of Residual Stresses of a Circumferential Joint of a Pipe by Heat-Sink Welding	p. 231
Prediction of Deformation Produced by Line Heating	p. 235
Simulation of Resistance Spot Welding Process	p. 236
Prediction of Welding Distortion Produced in Large Plate Structures	p. 239
References	p. 244
Residual Stress Distributions in Typical Welded Joints	p. 247
Residual Stresses in Base Metals	p. 248
Residual Stress in Thermo-Mechanical Control Process(TMCP) Steel	p. 248
Residual Stress in TMCP Steel Induced by Bead Weld	p. 250
Explosive Clad Steel	p. 251
Cylindrical Thick Plate by Cold Bending	p. 252
Residual Stresses in Welded Joints of Plates; in 2-Dimensional	p. 253
Butt-Welded Joints; Classification of Patterns of Residual Stress Distributions	p. 253
Long Butt-Welded Joint, Prediction Equation	p. 256
Built-Up Members ofT Shape and I Shape	p. 257
Built-Up Member of T Shape, Experiment	p. 259
Residual Stress and Inherent Displacement Induced by Slit Welds	p. 260
Mullripass Butt Welds of Thick Plates; 3-Dimensional	p. 263
Multipass Butt Welds of Thick Plates, Classification	p. 263
Multipass Butt Welds of Thick Plate, Experiment	p. 264
Electron Beam Welding, Thick Plate	p. 265
First Bead of Butt Joint; RCC (Rigidly Restrained Cracking) Test Specimen	p. 267
Multipass-Welded Corner Joint	p. 268
Fillet Welds: 3-Dimensional	p. 269
Single Fillet Welds	p. 269
Fillet Welds at the Joint of Web and Flange	p. 270
Repair Weld of Thick Plate	p. 271
Circumferential Welded Joint of Pipes	p. 274
Circumferential Welded Joint of PipesùHeat-Sink Welding	p. 274
Penetrating Pipe Joints in Nuclear Reactor	p. 279
References	p. 281
Published material properties for thermal elastic-plastic FEM analysis Located on the companion website at booksite.elsevier.com/9780123948045
Theory of three-dimensional thermal elastic-plastic creep analysis Located on the companion website at booksite.elsevier.com/9780123948045
Contents of Programs and Data on the Companion Website	p. 283
Index	p. 285
About the Authors	p. 291
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