Kirkwood / Suéry / Kapranos Semi-solid Processing of Alloys

1. Auflage 2009
ISBN: 978-3-642-00706-4
Verlag: Springer
Format: PDF
Kopierschutz: 1 - PDF Watermark

E-Book, Englisch, Band 124, 172 Seiten

Reihe: Springer Series in Materials Science

Semisolid metallurgy (SSM) is now some 37-years-old in terms of time from its conception and ?rst reduction to practice in the laboratory. In the intervening years, there has been a steadily growing body of research on the subject and the beginning of signi?cant industrial applications. The overall ?eld of SSM comprises today a large number of speci?c process routes, almost all of which fall in the category of either 'Rheocasting' or Thi- casting.' The former begins with liquid metal and involves agitation during partial solidi?cation followed by forming. The latter begins with solid metal of suitable structure and involves heating to the desired fraction solid and forming. Research over the past 37 years, and particularly over the last decade, has provided a detailed picture of process fundamentals and led to a wide range of speci?c SSM processes and process innovations. Industrial studies and actual p- duction experience are providing a growing picture of the process advantages and limitations. At this time, the conditions for eventual wide adoption of SSM appear favorable, both for nonferrous and ferrous alloys. It must, however, be recognized that major innovations, such as SSM become adopted only slowly by industries where capital costsarehigh,pro?tmarginsaremodest,andfailuretomeetcustomercommitments carries a high penalty.

Autoren/Hrsg.

Kirkwood, David H.

Suéry, Michel

Kapranos, Plato

Atkinson, Helen V.

Young, Kenneth P.

Inhaltsverzeichnis

1;Foreword;6
2;Preface;7
3;Contents;9
4;Part I Evolution and Design of Microstructure in Semisolid Alloys D.H. Kirkwood;13
4.1;1 Fundamental Aspects;14
4.1.1;1.1 General and Local Equilibrium in Alloy Systems;14
4.1.2;1.2 Nucleation;16
4.1.2.1;1.2.1 Homogeneous Nucleation;16
4.1.2.1.1;The Rate Equation;16
4.1.2.2;1.2.2 Heterogeneous Nucleation;19
4.1.2.3;1.2.3 Grain Refinement;20
4.1.3;1.3 Solid–Liquid Interface Structure;22
4.1.4;1.4 Morphological Instability;23
4.1.5;1.5 Grain Multiplication;25
4.1.6;1.6 The Growth and Spheroidization of Equiaxed Grains;26
4.2;2 Characterization of Microstructure in Semisolid Slurries;28
4.2.1;2.1 Fraction Solid;28
4.2.2;2.2 The Shape Factor;28
4.2.3;2.3 Contiguity and Continuity;30
4.3;3 Evolution of Microstructure in Semisolid Alloys;33
4.3.1;3.1 Introduction;33
4.3.2;3.2 Coarsening in Al–Cu Alloys;34
4.3.3;3.3 Coarsening in Al–Si Alloys;35
4.3.4;3.4 X-ray Microtomography of Alloy Slurries;39
4.4;4 Recent Developments in Slurry Formation;44
4.4.1;References for Part I Evolution and Design of Microstructure in Semisolid Alloys;47
5;Part II Rheology and Modeling M. Suery and H. Atkinson;48
5.1;5 Introduction and Definitions for Rheology and Modeling;49
5.2;6 Experimental Determination of Rheological Behavior;51
5.2.1;6.1 Partially Solidified Alloys;51
5.2.1.1;6.1.1 Experimental Methods;51
5.2.1.1.1;Rotation and Translation Viscometer;51
5.2.1.1.2;Fluidity Tests;53
5.2.1.2;6.1.2 Results Concerning Viscosity;54
5.2.1.3;6.1.3 Results on Fluidity;62
5.2.2;6.2 Partially Remelted Alloys;62
5.2.2.1;6.2.1 Experimental Methods;62
5.2.2.1.1;Shear Viscometer;62
5.2.2.1.2;Parallel Plate Compression;63
5.2.2.1.3;Direct Extrusion;64
5.2.2.1.4;Back Extrusion;64
5.2.2.1.5;Indentation;64
5.2.2.1.6;Drained Compression;65
5.2.2.1.7;Tension;66
5.2.2.2;6.2.2 Results in Terms of Apparent Viscosity;66
5.2.2.2.1;Influence of the Morphology of the Solid Phase;66
5.2.2.2.2;Influence of Shear Rate;68
5.2.2.2.3;Influence of the Solid Fraction;71
5.2.2.3;6.2.3 Results in Terms of Constitutive Behavior;71
5.2.3;6.3 Comparison Between Partially Solidified and Partially Remelted Alloys;72
5.2.4;6.4 Yield Stress;73
5.2.5;6.5 Concluding Remarks;74
5.3;7 Modeling of Semisolid Processing;76
5.3.1;7.1 Introductory Remarks on Modeling;76
5.3.2;7.2 Utility of Modeling;79
5.3.3;7.3 Use of the Structural Parameter for Modeling: Model of Brown and Coworkers;80
5.3.4;7.4 Use of a Yield Stress in Models;81
5.3.5;7.5 Finite Difference Modeling;82
5.3.5.1;7.5.1 One-phase Finite Difference Modeling;82
5.3.5.2;7.5.2 Two-phase Finite Difference Modeling;89
5.3.6;7.6 Finite Element Modeling;89
5.3.6.1;7.6.1 One-phase Finite Element Modeling;89
5.3.6.1.1;Zavaliangos and Lawley;89
5.3.6.1.2;Backer;89
5.3.6.1.3;Alexandrou, Burgos and Coworkers;90
5.3.6.1.4;Orgéas and Coworkers;94
5.3.6.2;7.6.2 Two-phase Finite Element Modeling;97
5.3.7;7.7 Models akin to Forging Models;101
5.3.7.1;7.7.1 Viscoplastic Constitutive Models;101
5.3.7.2;7.7.2 Model Based on Viscoelasticity and Thixotropy;101
5.3.8;7.8 Micromodeling;102
5.3.9;7.9 Concluding Remarks on Modeling;104
5.4;8 General Conclusions on Rheology and Modeling;105
5.4.1;References for Part II Rheology and Modeling;106
6;Part III Industrial Applications of Semisolid Processing Ken Young and Plato Kapranos;110
6.1;9 Introduction to Industrial Applications of Semisolid Processing;111
6.2;10 Raw Material;114
6.2.1;10.1 Semisolid Material Delivery Systems;115
6.2.2;10.2 Vertical Induction Slug Heating;115
6.2.3;10.3 Horizontal Induction Slug Heating;116
6.2.4;10.4 Horizontal Convection Slug Heating;118
6.2.5;10.5 Reheating of Solid Feedstock;118
6.2.6;10.6 Direct Slurry Production: Rheocasting/Thixomoulding;121
6.2.6.1;10.6.1 New Rheo-Casting Route;121
6.2.6.2;10.6.2 Semisolid Rheocasting;122
6.2.6.2.1;Low-Fraction Solid Slurry;123
6.2.7;10.7 Other Slurry Based systems;124
6.2.7.1;10.7.1 ``Semisolid'' Slugs from Slurry;124
6.2.7.2;10.7.2 Direct Slurry Forming;125
6.2.7.3;10.7.3 Thixomoulding;126
6.2.7.4;10.7.4 Rheo-Die casting Process;128
6.3;11 Process Control in Die Filling and Die Design;130
6.3.1;11.1 Die Temperature Control Systems;131
6.3.2;11.2 Parts Selection for Formability Evaluation;132
6.3.3;11.3 Injection System Evaluation;132
6.3.4;11.4 Fill Test Observations;133
6.3.5;11.5 Venting and Vacuum Assist;135
6.3.6;11.6 Runner, Gate Design and Injection Forces;136
6.3.7;11.7 Surface Quality;137
6.3.8;11.8 Summary of General Process Issues.;138
6.3.8.1;11.8.1 Raw Materials;138
6.3.8.2;11.8.2 Alloy Selection;138
6.4;12 Component Design Rules;139
6.4.1;12.1 Tolerances;139
6.4.2;12.2 Part Design Rules;139
6.4.3;12.3 Dimensioning;139
6.4.4;12.4 Cost Reductions in Product Design;140
6.5;13 Practical Applications in Use Today;141
6.6;14 The Future;150
6.6.1;References for Part III Industrial Applications of Semisolid Processing;151
7;Appendix to Industrial Applications of Semisolid Processing: Mechanical Properties of Some Thixoformed Alloys;151
7.1;References;165
8;Index;167