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| موضوع: كتاب Magnesium Injection Molding الإثنين 04 مايو 2020, 3:04 am | |
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أخوانى فى الله أحضرت لكم كتاب Magnesium Injection Molding Frank Czerwinski
و المحتوى كما يلي :
Contents Preface . vii 1 Magnesium and Its Alloys . 1 1.1 Introduction . 1 1.2 Market Development 1 1.2.1 Raw Metal Production . 1 1.2.2 Raw Metal Consumption . 4 1.3 Production Techniques of Pure Metal . 9 1.3.1 Thermal Processes 10 1.3.2 Electrolytic Methods 10 1.3.3 Experimental Scale Processes . 12 1.3.4 Recycling as a Source of the Secondary Metal 15 1.4 Fundamentals of Alloying 18 1.4.1 Role of Alloying Additions . 18 1.4.2 Impurities . 23 1.4.3 Strengthening Mechanisms . 24 1.5 Alloys . 29 1.5.1 Designations 29 1.5.2 Casting Alloys . 29 1.5.3 Wrought Alloys 35 1.5.4 Alloys Manufactured by Non-Conventional Methods . 38 1.6 Selected Properties of Alloys . 40 1.6.1 Deformation Mechanisms 40 1.6.2 Superplastic Deformation 45 1.6.3 Mechanical Properties . 46 1.6.4 Damping Capacity 49 1.6.5 EMI/RFI Shielding . 49 1.6.6 Heat Dissipation 51 1.7 Processing Techniques 52 1.7.1 Casting . 53 1.7.2 Forging . 58 1.7.3 Rolling . 59 xixii Contents 1.7.4 Extrusion 60 1.8 Heat Treatment . 61 1.8.1 Annealing 62 1.8.2 Stress Relieving . 62 1.8.3 Solution Treatment and Aging 62 1.9 Surface Protection . 65 1.9.1 Corrosion Nature 65 1.9.2 Metallurgical Factors Affecting Corrosion 67 1.9.3 Corrosion Prevention by Surface Treatments 68 1.10 Application Markets . 73 1.10.1 Automotive . 73 1.10.2 Aerospace 75 1.10.3 Consumer Electronics (3C) . 75 1.10.4 General Purpose Market . 76 1.11 Summary 76 References 76 2 Semisolid Processing — Origin of Magnesium Molding 81 2.1 Introduction . 81 2.2 Origin of the Concept . 81 2.2.1 Thixotropy 81 2.2.2 Semisolid Metal Processing . 82 2.3 Rheological Behavior of Semisolid Slurries 83 2.3.1 Newtonian and Non-Newtonian Fluids 83 2.3.2 Thixotropy and Pseudoplasticity . 85 2.3.3 Experimental Relationships for Metallic Slurries 86 2.3.4 Models Describing Thixotropic Behavior 87 2.3.5 Flow Characteristics 91 2.4 Viscosity Measurements of Metallic Slurries . 96 2.4.1 Rotational Instruments . 96 2.4.2 Compression Viscometer . 99 2.4.3 Drop Forge Viscometer 99 2.4.4 Back Extrusion Viscometer . 101 2.5 Rheological Measurements for Semisolid Magnesium Alloys 103 2.5.1 Isothermal Holding Measurements . 103 2.5.2 Continuous Cooling Measurements . 104 2.5.3 Influence of Rest Time on Viscosity 106 2.6 Techniques of Generating Globular Structures 107 2.6.1 Melt Stirring/Agitation 107 2.6.2 Chemical Grain Refinement 110 2.6.3 Swirl Enthalpy Equilibration 110 2.6.4 Continuous Rheo-Conversion Process (CRP) . 111 2.6.5 Liquidus/Sub-Liquidus Casting/Pouring . 112 2.6.6 Rapid Slug Cooling . 112Contents xiii 2.6.7 Controlled Slow Cooling . 113 2.6.8 Spray Forming . 113 2.6.9 Liquid Phase Sintering (LPS) . 115 2.6.10 Stress Induced Melt Activation (SIMA) . 115 2.7 Benefits of Semisolid Processing . 115 2.7.1 Structural Implications of Reduced Temperature 116 2.7.2 Component’s Integrity and Microstructure . 118 2.7.3 Present Limitations . 119 2.8 Suitability Criteria of Alloys for Semisolid Processing 119 2.8.1 Solidification Range 120 2.8.2 Temperature Sensitivity of Solid Fraction 120 2.8.3 Thermodynamic Characteristics of Alloys for Semisolid Processing . 121 2.8.4 Morphological and Rheological Characteristics of the Slurry 122 2.8.5 Applicability of Semisolid Processing for Magnesium Alloys . 122 2.9 Industrial Implementations of Major Semisolid Concepts 124 2.9.1 Rheo- and Thixo- Processing Routes . 124 2.9.2 Thixocasting 126 2.9.3 New Rheocasting (NRC) . 126 2.9.4 Semisolid Rheocasting (SSR) . 127 2.9.5 Sub-Liquidus Casting (SLC) 128 2.9.6 Other Semisolid Techniques 129 2.10 Origin and Progress of Magnesium Molding 130 2.10.1 Technology Origin 130 2.10.2 Commercialization Progress 134 2.11 Present Applications and Future Opportunities for Magnesium Molding 135 2.11.1 Consumer Electronics . 135 2.11.2 Automotive . 142 2.11.3 General Purpose Equipment 144 2.12 Summary 144 References 145 3 Basic and Auxiliary Hardware . 149 3.1 Introduction 149 3.2 Machine . 149 3.2.1 Clamp . 149 3.2.2 Injection Unit 154 3.2.3 Machine Barrel Assembly 155 3.2.4 Heating Systems for Barrel Assembly Components 158 3.2.5 Injection Screw Assembly 164 3.2.6 Feedstock Loading Devices . 166xiv Contents 3.2.7 Feedstock Drying and Preheating Devices . 168 3.2.8 Protective Gas Supply to the Barrel 169 3.2.9 Mist Filtration Devices 169 3.2.10 Robots . 169 3.2.11 Barrel and Screw Maintenance Stations . 170 3.3 Slurry Distribution Systems . 171 3.3.1 Cold Sprue 171 3.3.2 Hot Sprue . 172 3.3.3 Hot Runner . 172 3.4 Mold . 174 3.4.1 General Features . 174 3.4.2 Mold Heating–Cooling Systems . 175 3.4.3 Mold Spray Equipment 177 3.4.4 Mold Vacuum Systems 178 3.5 Summary 180 References 180 4 Thermal and Corrosive Aspects of Processing Molten Magnesium 181 4.1 Introduction 181 4.2 High-Temperature Effect of Molten Magnesium Alloys on Other Materials . 182 4.2.1 Property Degradation Due to Structural Changes 182 4.2.2 High Temperature Fatigue 188 4.2.3 Thermal Fatigue . 192 4.2.4 Corrosion Fatigue 194 4.2.5 Creep and Stress Rupture 194 4.2.6 Oxidation . 196 4.3 Corrosive Behavior of Molten Magnesium Alloys 199 4.3.1 Reactivity with Iron and Steel . 199 4.3.2 Reactivity with Ni-Containing Alloys . 202 4.3.3 Simultaneous Corrosion and Wear . 210 4.4 Summary 212 References 214 5 Process Theory and Practice . 215 5.1 Introduction 215 5.2 Key Processing Parameters 215 5.2.1 Injection Molding Sequence 215 5.2.2 Barrel Temperature Profile . 218 5.2.3 Shot Size . 220 5.2.4 Injection Profile 220 5.2.5 Recovery . 223 5.3 Functions of the Injection Screw . 223 5.3.1 Feedstock Conveying . 223Contents xv 5.3.2 Feedstock Melting 225 5.3.3 Alloy Metering 226 5.3.4 Output of Injection Screw 227 5.3.5 Shear Function of an Injection Screw . 229 5.3.6 Alloy Mixing 232 5.4 Function of the Non-Return Valve . 238 5.4.1 Role of Piston in Die Casting . 238 5.4.2 Role of the Non-Return Valve in Plastics Injection 241 5.4.3 Role of the Non-Return Valve in Magnesium Molding 241 5.5 Nozzle Plug—Principles of Thermal Gating . 242 5.5.1 Formation of the Nozzle Plug . 242 5.5.2 Mechanism of the Plug’s Release and Disintegration . 245 5.5.3 Plug Nature During Induction Heating 245 5.5.4 Slurry Transfer to the Mold Using Hot Sprue . 246 5.5.5 Slurry Distribution to the Mold Using Hot Runners . 249 5.6 Mold Processing . 251 5.6.1 Fluidity of Molten Metals 252 5.6.2 Mold Filling Time 256 5.6.3 Mold Temperature 260 5.6.4 Mold Spraying Function . 261 5.6.5 Part Cooling After Ejection . 264 5.7 Common Defects . 264 5.7.1 Defect Classification and Characterization . 264 5.7.2 Identifying Defect Causes 269 5.7.3 Defect Prediction by Flow Modeling . 277 5.8 Product Quality Control . 277 5.8.1 Dimensional Accuracy and Surface Quality 277 5.8.2 Integrity of the Component . 277 5.8.3 Chemistry 282 5.8.4 Metallography . 282 5.9 Summary . 282 References 283 6 Feedstock Selection 285 6.1 Introduction . 285 6.2 Techniques of Particulates Manufacturing . 285 6.2.1 Mechanical Comminution 286 6.2.2 Techniques Based on Rapid Solidification . 288 6.3 Characterization of Particulates Manufactured by Mechanical Fragmentation . 290 6.3.1 Morphological Features . 290 6.3.2 Sieve Analysis . 292 6.3.3 Bulk Density 295xvi Contents 6.3.4 External Defects . 295 6.3.5 Phase Composition and Microstructure . 296 6.4 Characterization of Rapidly Solidified Granules 297 6.4.1 Morphological Features . 297 6.4.2 Dimensional Features . 299 6.4.3 Bulk Density 301 6.4.4 External Defects . 301 6.4.5 Stability of Chemical Composition . 303 6.4.6 Phase Composition . 304 6.4.7 Internal Microstructure 305 6.4.8 Microstructure of Globules with External Defects . 307 6.5 External Characteristics Affecting Injection Molding Applications 308 6.5.1 Mechanically Fragmented Chips 309 6.5.2 Rapidly Solidified Granules 309 6.6 Global Manufacturing Market of Magnesium Particulates . 310 6.7 Summary . 312 References 312 7 Oxidation Behavior of the Feedstock 315 7.1 Introduction 315 7.2 Oxidation Kinetics 315 7.2.1 Initial Stage Reaction . 316 7.2.2 Transient and Steady Stage Reactions 318 7.3 Oxidation Surfaces 319 7.4 Oxide Growth Morphologies 320 7.4.1 Thin Films 320 7.4.2 Nodular Features . 321 7.5 Internal Structure of Oxide Layers 324 7.6 Oxide Phase Composition . 326 7.7 Influence of Chemical Composition on Magnesium Oxidation 330 7.8 Evaporation Characteristics . 332 7.9 Oxidation Mechanism 334 7.9.1 Initial Oxidation—Thin Film Stage 334 7.9.2 Transient Stage—Oxide Ridges . 334 7.9.3 Steady Stage Growth—Oxide Nodules . 336 7.9.4 Role of Substrate Phases in Oxide Growth . 337 7.10 Ignition Behavior . 338 7.11 Alloy Protection Against Oxidation and Ignition . 339 7.11.1 Sulphur Hexafluoride SF6 340 7.11.2 Sulphur Dioxide SO2 342 7.11.3 MagShield 342 7.11.4 Other Methods 343 7.11.5 Protective Atmospheres for Heat Treatment 345 7.11.6 Environmental Impact . 345Contents xvii 7.12 Implications for Injection Molding Practice . 346 7.12.1 Advantages of Oxidation Kinetics and an Incubation Period 346 7.12.2 No Accumulation of Magnesium Vapour—Protection by an Inert Gas 347 7.12.3 Issues Caused by the Particulate Nature of the Feedstock . 347 7.12.4 Advantage of Small Volume of Molten Alloy 347 7.13 Examples of Alloy Degradation from Injection Molding Practice 347 7.13.1 Magnesium Evaporation . 348 7.13.2 Oxidation Within a Machine Nozzle During Stand-By Periods 349 7.13.3 Oxidation and Ignition During Equipment Maintenance . 350 7.14 Summary 352 References 352 8 Melting Behavior of the Feedstock 355 8.1 Introduction 355 8.2 Factors Affecting Feedstock’s Thermal Instability 355 8.2.1 Cold Deformation in Metals 355 8.2.2 Cold Deformation of Magnesium 356 8.2.3 Compression Deformation of As-Cast Ingot . 357 8.2.4 Deformation in Mechanically Cut Chips 357 8.2.5 Deformation in Pellets Manufactured by Solid-State Extrusion . 359 8.3 Solid-State Transformation During Heating . 364 8.3.1 Phenomena During Annealing of Cold-Deformed Metal . 365 8.3.2 Recrystallization Phenomena in Magnesium . 366 8.3.3 Recrystallization of Cold-Deformed Ingot . 367 8.3.4 Annealing Phenomena Within Mechanically Comminuted Chips . 368 8.3.5 Annealing Phenomena in Extruded Pellets . 370 8.4 Microstructure Evolution During Feedstock Melting 374 8.4.1 Nature of Non-Equilibrium Melting 375 8.4.2 Melting by Liquid Penetration Along Grain Boundaries 375 8.4.3 Assessment of The Solid to Liquid Ratio During Melting 376 8.4.4 Melting Mechanically Comminuted Chips . 385 8.4.5 Melting of Extruded Pellets 387 8.5 Melting of As-Cast Ingot 392 8.6 Phenomena During Heating of Rapidly Solidified Granules . 394xviii Contents 8.6.1 Features of As-Solidified Microstructure 395 8.6.2 Transformations During Heating in Solid State . 396 8.6.3 Granule Melting . 396 8.6.4 Common Melting Features of Particulate Feedstock . 398 8.7 Microstructure Correlation Between the Solid and Semisolid State . 399 8.7.1 Solid-State Grain Versus Semisolid-State Solid Globule 400 8.7.2 Size-Evolution of Solid Phase Within the Slurry 401 8.7.3 Internal Changes of the Globular Solid 403 8.8 Summary . 403 References 404 9 Alloy Transformations During Molding . 407 9.1 Introduction . 407 9.2 Factors Controlling Microstructure Evolution 407 9.2.1 Slurry Generation 408 9.2.2 Secondary Changes During Injection . 409 9.2.3 Solidification Conditions 409 9.3 Solid-State Transformations During Initial Conveyance 409 9.4 Semisolid-State Transformations Within the Machine Barrel 412 9.4.1 Transformations Under a Regime of Partial Melting . 414 9.4.2 Transformations Under a Regime of Complete Melting and Partial Re-Solidification . 416 9.4.3 Effectiveness of Shear During Mold Filling 418 9.4.4 Transformations During Non-Conventional Processing . 419 9.5 Transformations Associated with the Seal Plug . 420 9.5.1 Role of Alloy Temperature in the Plug’s Microstructure . 420 9.5.2 Changes During Reheating, Preceding the Plug’s Release 420 9.5.3 Effect of Microstructure on Plug’s Disintegration . 421 9.5.4 Effect of Microstructure on Plug Flow Behavior Through the Mold Gate 423 9.6 Theories of the Formation of Globular Structures During Melting and Solidification . 425 9.6.1 Morphology of the Crystallization Front 425 9.6.2 Dendrite Description 426 9.6.3 Segregation in Cast Structures 426 9.6.4 Globular Growth Due to Fragmentation of Dendrites 427 9.6.5 Development of Globular Forms During Melting 428 9.6.6 Solidification of Remnant Liquid 429 9.7 Evolution of the Primary Solid Phase During Molding . 429 9.7.1 Characteristics of the Primary Solid After Various Processing Routes 429Contents xix 9.7.2 Particle Size Versus Solid Volume Fraction 430 9.7.3 Mechanisms Controlling the Solid Particle Evolution . 431 9.8 Engineering Microstructure for Commercial Applications . 436 9.8.1 Thick Wall Components . 436 9.8.2 Thin Wall Components 437 9.9 Summary 439 References . 439 10 Microstructure–Property Relationship for Molded Alloys . 441 10.1 Introduction 441 10.2 Parameters Characterizing Thixotropic Structures After Solidification 441 10.2.1 Volume Fraction of the Primary Solid 442 10.2.2 Size of the Primary Solid Particles . 443 10.2.3 Shape of the Primary Solid . 443 10.2.4 Volume of Entrapped Liquid 446 10.2.5 Interfaces . 446 10.3 General Constituents of Thixotropic Microstructures of Magnesium Alloys 447 10.3.1 Primary Solid . 448 10.3.2 As-Solidified Liquid 448 10.3.3 Phase Composition . 449 10.3.4 Structural Integrity . 451 10.4 Internal Structure of the Primary Solid and Matrix . 452 10.4.1 Entrapped Liquid in As-Cast State . 452 10.4.2 Changes of Entrapped Liquid Due to Diffusion . 452 10.4.3 Detailed Features of Molded Structures . 454 10.5 Tensile Properties . 456 10.6 Decohesion Characteristics 457 10.6.1 Failure Mode Under Cryogenic Conditions 459 10.7 Structure–Property Correlation . 462 10.7.1 Role of Alloy Matrix 462 10.7.2 Role of Solid Particle Substructure . 462 10.7.3 Role of Solid Particle Content 463 10.8 Attempts at a Quantitative Description of the Structure– Property Relationship 463 10.9 Structure–Property Correlation for Magnesium Alloys, Processed with Other Semisolid Techniques 465 10.10 Modification of Mechanical Properties by the Post-Molding Heat Treatment 466 10.11 Summary 466 References . 467xx Contents 11 Semisolid Extrusion Molding . 469 11.1 Introduction . 469 11.2 General Features of SSEM . 469 11.2.1 Deformation Behavior of Slurries at Ultra High Solid Contents . 470 11.2.2 Temperature Requirements for SSEM . 471 11.3 Mold Filling Characteristics and Part Integrity 471 11.3.1 Flow Behavior of the High-Solid Slurries 471 11.3.2 Part Integrity . 472 11.3.3 Mold Filling Time as the Critical Factor 474 11.3.4 Role of the Flow Mode . 476 11.4 Structural Transformations During Molding and As-Solidified Structure . 476 11.4.1 Structural Transformations During SSEM 476 11.4.2 General Microstructure After Solidification . 477 11.4.3 Role of the Solidification Rate . 478 11.4.4 Phase Composition 480 11.5 Characterization of Primary Solid . 481 11.5.1 Factors Affecting Solid Distribution . 481 11.5.2 The Size of Solid Particles and Its Change During Processing . 482 11.6 Application Areas for SSEM . 484 11.7 Summary . 485 References . 485 12 Near-Liquidus Molding 487 12.1 Introduction . 487 12.2 Growth of Globular Structures by Nucleation 487 12.2.1 Mullins–Sekerka Stability Criterion of Globular Growth 488 12.2.2 Growth of Globular Forms During Non-Agitated Solidification . 489 12.2.3 Growth of Globular Forms Under Forced Convection 491 12.3 The NLM Concept and Its Experimental Implementation 492 12.3.1 Technical Implications of the Preheating Range Required . 493 12.3.2 Preheating Range for Mg–Al–Zn Alloys . 493 12.4 Microstructure After NLM . 494 12.4.1 Alloy’s Structural Integrity 495 12.4.2 Matrix Morphology 497 12.4.3 Morphology of Solid Particles . 498 12.4.4 Features of Die Cast Microstructure . 499 12.4.5 Crystallographic Orientation . 500Contents xxi 12.4.6 Phase Composition 500 12.4.7 Decohesion Characteristics 502 12.5 Tensile Properties 504 12.6 Structure-Property Correlation After NLM 505 12.6.1 Benefits of Reduced Temperatures During NLM . 506 12.6.2 Melt Agitation During NLM . 506 12.6.3 Separating the Microstructure and Internal Integrity 507 12.6.4 Influence Of Alloy’s Chemistry 507 12.7 Application Areas of NLM . 508 12.7.1 Thin-wall Molding 508 12.7.2 Matrix for Composites . 508 12.8 Summary . 510 References . 510 13 Alloy and Composite Generation in a Semisolid State . 513 13.1 Introduction . 513 13.2 Concept of Semisolid-State Mixing 513 13.2.1 Methods of Practical Implementation 514 13.2.2 Phenomenology of Structural Transformations 514 13.3 Effect of Temperature on Semisolid-State Mixing . 516 13.3.1 Chemistry and Phase Composition 517 13.3.2 Role of a Particulate Nature of the Feedstock During Mixing . 520 13.3.3 Microstructure Evolution . 521 13.3.4 Effect of Solid State Diffusion . 523 13.4 Role of Other Parameters in Semisolid-State Mixing . 523 13.4.1 Proportions of Mixed Ingredients . 524 13.4.2 Differences in Melting Ranges . 525 13.5 Tensile Properties of Alloys Created by Semisolid-State Mixing . 526 13.5.1 Correlation of Strength and Elongation 526 13.5.2 Influence of Mixing Temperature on Properties 527 13.5.3 Applicability of the Rule of Mixtures 532 13.6 Generation of Magnesium Matrix Composites 532 13.6.1 Magnesium as a Composite’s Matrix 533 13.6.2 Reinforcements Applicable for Magnesium . 535 13.6.3 Challenges with Manufacture of the Magnesium Matrix Composites 536 13.6.4 Injection Molding as a Fabrication Method of Composites 536 13.7 Engineering Importance of Semisolid-State Mixing . 540 13.7.1 Application to Conventional Alloys . 540 13.7.2 Application to Immiscible Alloys . 540 13.7.3 Application to Magnesium Matrix Composites 541 13.8 Summary . 541 References . 542xxii Contents 14 Molding Creep-Resistant Alloys . 543 14.1 Introduction . 543 14.2 Elements of Creep Deformation Theory . 544 14.2.1 The Creep Deformation Curve . 544 14.2.2 Creep Mechanisms 546 14.3 Creep in Magnesium and Its Alloys 547 14.3.1 Creep in Pure Magnesium . 548 14.3.2 Factors Affecting Creep in Magnesium Alloys 548 14.4 Creep Control in Modern Commercial Alloys 550 14.4.1 Alloying Systems . 551 14.4.2 Role of Alloy Processing in Creep Properties . 553 14.5 Characteristics of Mg–5Al–2Sr Feedstock for Injection Molding . 554 14.5.1 Alloy Chemistry and Melting Range 554 14.5.2 Effect of Sr on Phase Composition in As-Cast Ingot 555 14.5.3 General Microstructure . 557 14.5.4 Ingot’s Phases and Their Morphology . 560 14.5.5 Changes During Manufacturing to Particulates 562 14.6 Effect of Semisolid Molding on Mg–5Al–2Sr Microstructure . 563 14.6.1 Phase Composition 564 14.6.2 General Microstructure . 565 14.6.3 Phase Morphology 569 14.7 Summary . 570 References . 573 Index . 575
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