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Semi-solid Processing of Alloys

:	David H. Kirkwood, Michel Suéry, Plato Kapranos, Helen V. Atkinson, Kenneth P. Young
:	Semi-solid Processing of Alloys
:	Springer-Verlag
:	9783642007064
:	1
:	CHF 74.40
:

:	Maschinenbau, Fertigungstechnik
:	English

:	172
:	Wasserzeichen/DRM
:	PC/MAC/eReader/Tablet
:	PDF

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?tmarginsarem dest,andfailuretomeetcustomer ommitments carries a high penalty.

	Foreword	6
	Preface	7
	Contents	9
	Part I Evolution and Design of Microstructure in Semisolid Alloys D.H. Kirkwood	13
	1 Fundamental Aspects	14
	1.1 General and Local Equilibrium in Alloy Systems	14
	1.2 Nucleation	16
	1.2.1 Homogeneous Nucleation	16
	The Rate Equation	16
	1.2.2 Heterogeneous Nucleation	19
	1.2.3 Grain Refinement	20
	1.3 Solid Liquid Interface Structure	22
	1.4 Morphological Instability	23
	1.5 Grain Multiplication	25
	1.6 The Growth and Spheroidization of Equiaxed Grains	26
	2 Characterization of Microstructure in Semisolid Slurries	28
	2.1 Fraction Solid	28
	2.2 The Shape Factor	28
	2.3 Contiguity and Continuity	30
	3 Evolution of Microstructure in Semisolid Alloys	33
	3.1 Introduction	33
	3.2 Coarsening in Al Cu Alloys	34
	3.3 Coarsening in Al Si Alloys	35
	3.4 X-ray Microtomography of Alloy Slurries	39
	4 Recent Developments in Slurry Formation	44
	References for Part I Evolution and Design of Microstructure in Semisolid Alloys	47
	Part II Rheology and Modeling M. Suery and H. Atkinson	48
	5 Introduction and Definitions for Rheology and Modeling	49
	6 Experimental Determination of Rheological Behavior	51
	6.1 Partially Solidified Alloys	51
	6.1.1 Experimental Methods	51
	Rotation and Translation Viscometer	51
	Fluidity Tests	53
	6.1.2 Results Concerning Viscosity	54
	6.1.3 Results on Fluidity	62
	6.2 Partially Remelted Alloys	62
	6.2.1 Experimental Methods	62
	Shear Viscometer	62
	Parallel Plate Compression	63
	Direct Extrusion	64
	Back Extrusion	64
	Indentation	64
	Drained Compression	65
	Tension	66
	6.2.2 Results in Terms of Apparent Viscosity	66
	Influence of the Morphology of the Solid Phase	66
	Influence of Shear Rate	68
	Influence of the Solid Fraction	71
	6.2.3 Results in Terms of Constitutive Behavior	71
	6.3 Comparison Between Partially Solidified and Partially Remelted Alloys	72
	6.4 Yield Stress	73
	6.5 Concluding Remarks	74
	7 Modeling of Semisolid Processing	76
	7.1 Introductory Remarks on Modeling	76
	7.2 Utility of Modeling	79
	7.3 Use of the Structural Parameter for Modeling: Model of Brown and Coworkers	80
	7.4 Use of a Yield Stress in Models	81
	7.5 Finite Difference Modeling	82
	7.5.1 One-phase Finite Difference Modeling	82
	7.5.2 Two-phase Finite Difference Modeling	89
	7.6 Finite Element Modeling	89
	7.6.1 One-phase Finite Element Modeling	89
	Zavaliangos and Lawley	89
	Backer	89
	Alexandrou, Burgos and Coworkers	90
	Orgéas and Coworkers	94
	7.6.2 Two-phase Finite Element Modeling	97
	7.7 Models akin to Forging Models	101
	7.7.1 Viscoplastic Constitutive Models	101
	7.7.2 Model Based on Viscoelasticity and Thixotropy	101
	7.8 Micromodeling	102
	7.9 Concluding Remarks on Modeling	104
	8 General Conclusions on Rheology and Modeling	105
	References for Part II Rheology and Modeling	106
	Part III Industrial Applications of Semisolid Processing Ken Young and Plato Kapranos	110
	9 Introduction to Industrial Applications of Semisolid Processing	111
	10 Raw Material	114
	10.1 Semisolid Material Delivery Systems	115
	10.2 Vertical Induction Slug Heating	115
	10.3 Horizontal Induction Slug Heating	116
	10.4 Horizontal Convection Slug Heating	118
	10.5 Reheating of Solid Feedstock	118
	10.6 Direct Slurry Production: Rheocasting/Thixomoulding	121
	10.6.1 New Rheo-Casting Route	121
	10.6.2 Semisolid Rheocasting	122
	Low-Fraction Solid Slurry	123
	10.7 Other Slurry Based systems	124
	10.7.1 ``Semisolid'' Slugs from Slurry	124
	10.7.2 Direct Slurry Forming	125
	10.7.3 Thixomoulding	126
	10.7.4 Rheo-Die casting Process	128
	11 Process Control in Die Filling and Die Design	130
	11.1 Die Temperature Control Systems	131
	11.2 Parts Selection for Formability Evaluation	132
	11.3 Injection System Evaluation	132
	11.4 Fill Test Observations	133
	11.5 Venting and Vacuum Assist	135
	11.6 Runner, Gate Design and Injection Forces	136
	11.7 Surface Quality	137
	11.8 Summary of General Process Issues.	138
	11.8.1 Raw Materials	138
	11.8.2 Alloy Selection	138
	12 Component Design Rules	139
	12.1 Tolerances	139
	12.2 Part Design Rules	139
	12.3 Dimensioning	139
	12.4 Cost Reductions in Product Design	140
	13 Practical Applications in Use Today	141
	14 The Future	150
	References for Part III Industrial Applications of Semisolid Processing	151
	Appendix to Industrial Applications of Semisolid Processing: Mechanical Properties of Some Thixoformed Alloys	151
	References	165
	Index	167