Principles of Laser Materials Processing

PREFACE TO THE SECOND EDITION xxi PREFACE TO THE FIRST EDITION xxiii ABOUT THE COMPANION WEBSITE xxv PART I PRINCIPLES OF INDUSTRIAL LASERS 1 1 Laser Background 3 1.1 Laser Generation 3 1.2 Optical Resonators 12 1.3 Laser Pumping 21 1.4 System Levels 24 1.5 Broadening Mechanisms 26 1.6 Beam Modification 29 1.7 Beam Characteristics 35 1.8 Summary 43 2 Types of Lasers 55 2.1 Solid-State Lasers 55 2.2 Gas Lasers 57 2.3 Semiconductor (Diode) Lasers 69 2.4 New Developments in Industrial Laser Technology 80 2.5 Summary 89 3 Beam Delivery 95 3.1 The Electromagnetic Spectrum 95 3.2 Birefringence 96 3.3 Brewster Angle 96 3.4 Polarization 98 3.5 Beam Expanders 101 3.6 Beam Splitters 102 3.7 Beam Delivery Systems 103 3.8 Beam Shaping 116 3.9 Summary 125 PART II ENGINEERING BACKGROUND 133 4 Heat and Fluid Flow 135 4.1 Energy Balance During Processing 135 4.2 Heat Flow in the Workpiece 136 4.3 Fluid Flow in Molten Pool 156 4.4 Summary 161 5 The Microstructure 175 5.1 Process Microstructure 175 5.2 Discontinuities 195 5.3 Summary 202 6 Solidification 209 6.1 Solidification Without Flow 209 6.2 Solidification with Flow 216 6.3 Rapid Solidification 221 6.4 Summary 222 7 Residual Stresses and Distortion 227 7.1 Causes of Residual Stresses 227 7.2 Basic Stress Analysis 232 7.3 Effects of Residual Stresses 237 7.4 Measurement of Residual Stresses 240 7.5 Relief of Residual Stresses and Distortion 250 7.6 Summary 252 PART III LASER MATERIALS PROCESSING 261 8 Background on Laser Processing 263 8.1 System-Related Parameters 263 8.2 Process Efficiency 272 8.3 Disturbances That Affect Process Quality 274 8.4 General Advantages and Disadvantages of Laser Processing 275 8.5 Summary 275 9 Laser Cutting and Drilling 279 9.1 Laser Cutting 279 9.2 Laser Drilling 308 9.3 New Developments 318 9.4 Summary 326 10 Laser Welding 335 10.1 Laser Welding Parameters 335 10.2 Welding Efficiency 344 10.3 Mechanism of Laser Welding 344 10.4 Material Considerations 355 10.5 Weldment Discontinuities 359 10.6 Advantages and Disadvantages of Laser Welding 360 10.7 Special Techniques 360 10.8 Specific Applications 371 10.9 Summary 382 11 Laser Surface Modification 391 11.1 Laser Surface Heat Treatment 391 11.2 Laser Surface Melting 413 11.3 Laser Direct Metal Deposition 414 11.4 Laser Physical Vapor Deposition (LPVD) 419 11.5 Laser Shock Peening 420 11.6 Laser Texturing 427 11.7 Summary 429 12 Laser Forming 437 12.1 Principle of Laser Forming 437 12.2 Process Parameters 439 12.3 Laser-Forming Mechanisms 439 12.4 Process Analysis 443 12.5 Advantages and Disadvantages 447 12.6 Applications 448 12.7 Summary 448 13 Additive Manufacturing 453 13.1 Computer-Aided Design 453 13.2 Part Building 462 13.3 Post-Processing 477 13.4 Applications 478 13.5 Advantages and Disadvantages 480 13.6 Summary 480 14 Medical and Nanotechnology Applications of Lasers 485 14.1 Medical Applications 485 14.2 Nanotechnology Applications 490 14.3 Summary 494 15 Sensors for Process Monitoring 497 15.1 Laser Beam Monitoring 497 15.2 Process Monitoring 504 15.3 Summary 522 16 Processing of Sensor Outputs 527 16.1 Signal Transformation 527 16.2 Data Reduction 532 16.3 Pattern Classification 534 16.4 Summary 550 17 Laser Safety 557 17.1 Laser Hazards 557 17.2 Laser Classification 562 17.3 Preventing Laser Accidents 563 17.4 Summary 569 Appendix 17.A 571 Problem 572 Bibliography 572 Index 573