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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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