Magnesium Injection Molding (eBook)

Dr. Czerwinski did 2 years of postdoctoral study at McGill University and 2 years at McMaster University.  He has a PhD in Metallurgical Engineering from McGill University, and  a PhD in Materials Engineering from the University of Mining and Metallurgy, Cracow, Poland.  He was a University Professor of Materials and Metallurgical Engineering and a faculty member for 19 years.  Dr. Czerwinski has been a manager and principal scientist of numerous research projects sponsored by the National Research Council of Canada, universities and industry.  At present, he is a Chief Metallurgist involved in a development of the injection molding machinery and researching metallurgical aspects of semisolid injection molding of metallic alloys. He is the author of a monograph in surface engineering; and the author and co-author of over 140 reserch papers in peer-review scientific journals and conference proceedings. Dr.Czerwinski is affiliated with: Professional Engineergs of Ontario, ASM International and The Minerals, Metals and Materials Society.

Preface 6
Biography 8
Contents 9
Magnesium and Its Alloys 21
1.1 Introduction 21
1.2 Market Development 21
1.3 Production Techniques of Pure Metal 29
1.4 Fundamentals of Alloying 38
1.5 Alloys 49
1.6 Selected Properties of Alloys 60
1.7 Processing Techniques 72
1.8 Heat Treatment 81
1.9 Surface Protection 85
1.10 Application Markets 93
1.11 Summary 96
References 96
Semisolid Processing—Origin of Magnesium Molding 100
2.1 Introduction 100
2.2 Origin of the Concept 100
2.3 Rheological Behavior of Semisolid Slurries 102
2.4 Viscosity Measurements of Metallic Slurries 115
2.5 Rheological Measurements for Semisolid Magnesium Alloys 122
2.6 Techniques of Generating Globular Structures 126
2.7 Benefits of Semisolid Processing 134
2.8 Suitability Criteria of Alloys for Semisolid Processing 138
2.9 Industrial Implementations of Major Semisolid Concepts 143
2.10 Origin and Progress of Magnesium Molding 149
2.11 Present Applications and Future Opportunities for Magnesium Molding 154
2.12 Summary 163
References 164
Basic and Auxiliary Hardware 167
3.1 Introduction 167
3.2 Machine 167
3.3 Slurry Distribution Systems 189
3.4 Mold 192
3.5 Summary 198
References 198
Thermal and Corrosive Aspects of Processing Molten Magnesium 199
4.1 Introduction 199
4.2 High Temperature Effect of Molten Magnesium Alloys on Other Materials 200
4.3 Corrosive Behavior of Molten Magnesium Alloys 217
4.4 Summary 230
References 232
Process Theory and Practice 233
5.1 Introduction 233
5.2 Key Processing Parameters 233
5.3 Functions of the Injection Screw 241
5.4 Function of the Non-Return Valve 256
5.5 Nozzle Plug—Principles of Thermal Gating 260
5.6 Mold Processing 269
5.7 Common Defects 282
5.8 Product Quality Control 295
5.9 Summary 300
References 301
Feedstock Selection 303
6.1 Introduction 303
6.2 Techniques of Particulates Manufacturing 303
6.3 Characterization of Particulates Manufactured by Mechanical Fragmentation 308
6.4 Characterization of Rapidly Solidified Granules 315
6.5 External Characteristics Affecting Injection Molding Applications 326
6.6 Global Manufacturing Market of Magnesium Particulates 328
6.7 Summary 330
References 330
Oxidation Behavior of the Feedstock 332
7.1 Introduction 332
7.2 Oxidation Kinetics 332
7.3 Oxidation Surfaces 336
7.4 Oxide Growth Morphologies 337
7.5 Internal Structure of Oxide Layers 341
7.6 Oxide Phase Composition 343
7.7 Influence of Chemical Composition on Magnesium Oxidation 347
7.8 Evaporation Characteristics 349
7.9 Oxidation Mechanism 351
7.10 Ignition Behavior 355
7.11 Alloy Protection Against Oxidation and Ignition 356
7.12 Implications for Injection Molding Practice 363
7.13 Examples of Alloy Degradation from Injection Molding Practice 364
7.14 Summary 369
References 369
Melting Behavior of the Feedstock 371
8.1 Introduction 371
8.2 Factors Affecting Feedstock’s Thermal Instability 371
8.3 Solid-State Transformation During Heating 380
8.4 Microstructure Evolution During Feedstock Melting 390
8.5 Melting of As-Cast Ingot 408
8.6 Phenomena During Heating of Rapidly Solidified Granules 410
8.7 Microstructure Correlation Between the Solid and Semisolid State 415
8.8 Summary 419
References 420
Alloy Transformations During Molding 422
9.1 Introduction 422
9.2 Factors Controlling Microstructure Evolution 422
9.3 Solid-State Transformations During Initial Conveyance 424
9.4 Semisolid-State Transformations Within the Machine Barrel 427
9.5 Transformations Associated with the Seal Plug 435
9.6 Theories of the Formation of Globular Structures During Melting and Solidification 440
9.7 Evolution of the Primary Solid Phase During Molding 444
9.8 Engineering Microstructure for Commercial Applications 451
9.9 Summary 454
References 454
Microstructure–Property Relationship for Molded Alloys 456
10.1 Introduction 456
10.2 Parameters Characterizing Thixotropic Structures After Solidification 456
10.3 General Constituents of Thixotropic Microstructures of Magnesium Alloys 462
10.4 Internal Structure of the Primary Solid and Matrix 467
10.5 Tensile Properties 471
10.6 Decohesion Characteristics 472
10.7 Structure–Property Correlation 477
10.8 Attempts at a Quantitative Description of the Structure– Property Relationship 478
10.9 Structure–Property Correlation for Magnesium Alloys, Processed with Other Semisolid Techniques 480
10.10 Modification of Mechanical Properties by the Post- Molding Heat Treatment 481
10.11 Summary 481
References 482
Semisolid Extrusion Molding 484
11.1 Introduction 484
11.2 General Features of SSEM 484
11.3 Mold Filling Characteristics and Part Integrity 486
11.4 Structural Transformations During Molding and As- Solidified Structure 491
11.5 Characterization of Primary Solid 496
11.6 Application Areas for SSEM 499
11.7 Summary 500
References 500
Near-Liquidus Molding 501
12.1 Introduction 501
12.2 Growth of Globular Structures by Nucleation 501
12.3 The NLM Concept and Its Experimental Implementation 507
12.4 Microstructure After NLM 508
12.5 Tensile Properties 518
12.6 Structure-Property Correlation After NLM 519
12.7 Application Areas of NLM 522
12.8 Summary 524
References 524
Alloy and Composite Generation in a Semisolid State 526
13.1 Introduction 526
13.2 Concept of Semisolid-State Mixing 526
13.3 Effect of Temperature on Semisolid-State Mixing 529
13.4 Role of Other Parameters in Semisolid-State Mixing 536
13.5 Tensile Properties of Alloys Created by Semisolid- State Mixing 539
13.6 Generation of Magnesium Matrix Composites 545
13.7 Engineering Importance of Semisolid-State Mixing 553
13.8 Summary 554
References 555
Molding Creep-Resistant Alloys 556
14.1 Introduction 556
14.2 Elements of Creep Deformation Theory 557
14.3 Creep in Magnesium and Its Alloys 560
14.4 Creep Control in Modern Commercial Alloys 563
14.5 Characteristics of Mg–5Al–2Sr Feedstock for Injection Molding 567
14.6 Effect of Semisolid Molding on Mg–5Al–2Sr Microstructure 576
14.7 Summary 583
References 586
Index 588