Thixoforming : Semi-solid Metal Processing

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4.4 Development of Aluminium–Lithium-Alloys for Semi-solid Processing The concept of adaptation/optimization of familiar Al–Li alloys for processing in a partially liquid state is essentially based on the following points: . influencing the micro-grain structure and the texture properties by suitable selection of the composition and the process sequence; . optimization of the degree of recrystallization and the grain size in relation to the applicable component geometry; . adaptation of the casting grain structure by addition of elements such as Ce, Sc, Ti, B and Ag; . minimization of the proportions of balancing phases T2 and d, of Fe and Si phases, of Na and K and of hydrogen in solution; . variations in the main alloying elements (Li, Mg, Cu, Sc, etc.). The semiempirical methodology and sub-operations employed are shown in Figure 4.10. After selecting suitable Al–Li–X basis systems, first an evaluation was made of the important key parameters for processing in a partially liquid state, with the aid of thermochemical calculations. After tuning of the alloys by means of microalloying element additives, melt-based metallurgical synthesis of trial alloys as well the characterization was performed. Finally, thixocast and rheocast principle parts and real components were jointly produced and evaluated. Where necessary, an adaptation of the selected alloy composition was carried out in addition to repeating the development operation for reproducibility check. 4.4.1 Thermochemical Modelling 4.4 Development of Aluminium–Lithium-Alloys for Semi-solid Processingj121 The thermochemical calculations in the selected Al–Li–X system models [27–29] produced the following results, compared with experimental data [30]: . In the Al–Li–Cu system, the alloys AlLi4Cu4 (A3) and AlLi2.5Cu4 (A2) display the lowest temperature sensitivity in the liquid-phase portion. Both are below the critical value of dfl/dT < 0.015 for a liquid-phase proportion of 50% and therefore should be suitable for processing in the semi-solid range. The alloys AlLi2.5Cu2.5 (A1) and AlLi4Cu1.5 (A4) display a smaller processing window in relation to temperature sensitivity of the liquid-phase portion, but should prove of interest for processing with low liquid-phase proportions (
122j 4 Design of Al and Al–Li Alloys for Thixoforming Figure 4.10 Flow diagram of the methodology applied for adaptation of Al–Li–X alloys to thixoforming. should be suitable for processing in the semi-solid range. Similarly to the argument for A1 and A4, the alloy AlLi2.5Mg4 (A6) should be suitable for processing with low liquid-phase proportions (
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Thixoforming Semi-solid Metal Proce
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Further Reading Herlach, D. M. (ed.
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The Editors Prof. Dr. G. Hirt Insti
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VI Contents 1.3.5.2 Other Aluminium
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VIII Contents 4.6.1 Thixocasting 13
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X Contents 7.4.2 Isothermal Non-ste
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XII Contents 9.4.1.3 Simulation Res
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Preface Semi-solid forming of metal
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XVIII List of Contributors Andreas
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XX List of Contributors Alexander S
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2j 1 Semi-solid Forming of Aluminiu
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10j 1 Semi-solid Forming of Alumini
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Table 1.1 Overview of semi-solid pr
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Part One Material Fundamentals of M
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32j 2 Metallurgical Aspects of SSM
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44j 3 Material Aspects of Steel Thi
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172j 6 Modelling the Flow Behaviour
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7 A Physical and Micromechanical Mo
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3. Macroscopic averages or homogeni
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displacement boundary conditions or
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and liquid are both assumed to be i
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are the strain rate concentration t
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Semi-solid viscosity (Pa s) into cl
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Load (kN) strain to rupture, leadin
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Load (kN) 7 6 5 4 3 2 1 0 0 7.5 Con
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adius R radius of the spherical inc
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Part Three Tool Technologies for Fo
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242j 8 Tool Technologies for Formin
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9 Rheocasting of Aluminium Alloys a
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Figure 9.2 Processes for the semi-s
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Two Italian companies gained the fi
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9.2 SSM Casting Processesj317 For t
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Figure 9.7 Oil pump cover for Honda
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Figure 9.9 Middle temperature cours
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Figure 9.12 Components of cartridge
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Figure 9.15 Process adapted multipa
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step-shot experiments. It is also s
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Figure 9.18 (a) Meander tool for fl
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Figure 9.19 (a, b) Wear appears in
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Table 9.2 Temperature determination
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and are plausible on the left. Furt
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Figure 9.27 Development of the micr
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some places can be observed as smal
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Figure 9.31 Simulation of the metal
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Figure 9.33 So-called Constant Temp
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Figure 9.35 Comparison of the micro
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9.4 Rheoroutej347 If rounding of th
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9.4.1.2 Parameters: Cooling to the
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Figure 9.36 Results of the 2D-MICRE
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homogeneous microstructure and no d
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grain fragment density [mm -1 ] 200
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can be considered for rheocasting o
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Figure 9.44 Microstructure of Zr/Sc
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Figure 9.45 MAGMAsoft simulation: c
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The cooling to the process temperat
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D grain diameter of a circle DGM De
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27 Doppelbauer, M. (2003) Wirtschaf
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10 Thixoforging and Rheoforging of
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1970s [7]. Also, the quality of the
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10.3 Heating and Forming Operations
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With the solution of the Equations
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10.3.1.2 Modelling of Inductive Hea
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material properties have to be cons
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10.3 Heating and Forming Operations
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Figure 10.9 Experimental results, d
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Figure 10.12 Segregation in compone
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10.3.4 Thixoforging of Steel In thi
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10.3.5 Thixojoining of Steel In the
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einforcing element. The possibiliti
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Figure 10.20 The robot controller a
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Figure 10.21 Experimental results w
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Figure 10.24 Design and working pri
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The investigations show that the rh
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Figure 10.31 Scheme of the heat tra
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Table 10.2 Definition of boundary c
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Figure 10.35 Experimental and simul
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References 1 Koesling, D., Tinius,
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steel billets into the semi-solid s
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412j 11 Thixoextrusion The followin
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414j 11 Thixoextrusion channel with
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416j 11 Thixoextrusion parameter co
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418j 11 Thixoextrusion Both concept
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420j 11 Thixoextrusion should be ju
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422j 11 Thixoextrusion Figure 11.8
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424j 11 Thixoextrusion Table 11.4 C
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426j 11 Thixoextrusion Temperature
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428j 11 Thixoextrusion impacts. Ext
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432j 11 Thixoextrusion shell format
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436j 11 Thixoextrusion Table 11.6 P
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440j 11 Thixoextrusion solidificati
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442j 11 Thixoextrusion GPa pressure
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444j Index arbitrary volume element
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446j Index equilibrium tests 141 eq
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448j Index - importance 273 ion flu
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450j Index oxygen-sensitive element
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452j Index - thixoforming 241 semi-
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454j Index - high pressure 131 - sc
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Thixoforming : Semi-solid Metal Processing

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