Thixoforming : Semi-solid Metal Processing

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6.1.6 Experimental Results and Modelling 6.1.6.1 Rotational Rheometer The experimental procedures conducted to analyse the flow behaviour of the metallic suspensions include all the varieties listed in Table 6.1. Shear Rate Jump Experiments The shear rate jump experiments served to identify steady-state flow curves and also thixotropic effects after a sudden change in shear rate. The influence of solid fraction on the flow behaviour of X210CrW12 is shown in Figure 6.14. After material preparation, the shear rate was decreased to 50 s 1 followed by consecutive shear jumps up to 225 s 1 . The shear rate jump experiments show the shear-thinning and time-dependent flow properties of semi-solid X210CrW12. Furthermore, it can be seen that the agglomeration process of solid particles occurring during a decrease in shear rate is slower than the deagglomeration process when shear rate increases. Taking a closer look at the flow behaviour immediately after a change in shear rate (Figure 6.15), isostructural attributes, a phenomenon discussed in the literature, Figure 6.14 Shear rate jumps and corresponding viscosity curves for different solid fractions. Material: X210CrW12. Figure 6.15 Slope of the viscosity immediately after a change in shear rate. 6.1 Empirical Analysis of the Flow Behaviourj183
184j 6 Modelling the Flow Behaviour of Semi-solid Metal Alloys Figure 6.16 Equilibrium viscosity curves for different solid fractions. Material: X210CrW12. become apparent. The agglomeration state is assumed to remain constant momentarily if the shear rate is suddenly changed from a basis shear rate to a higher or lower one. As a result, Newtonian flow behaviour is anticipated, but, as already observed for tin–lead [12, 27] and aluminium alloys [13, 22]. So far, this phenomenon cannot be explained. In the model approach (Equation 6.3) the flow exponent m describes the isostructural behaviour when k remains constant. Figure 6.16 shows the steady-state flow curves generated from Figure 6.14. Figure 6.17 more clearly displays the flow curve for the liquid material ( fs ¼ 0%), which shows as expected Newtonian properties with a viscosity of 50 mPa s. The high fluctuations in the liquid measurements result from the bearing of the rod as the momentum of the bearing is in the range of that from the liquid metal. The shear rate jump experiments are used to calculate initial model parameters from Equation 6.3, which in turn can be utilized for the more exact inverse parameter determination described in Section 6.2.4.2. Figure 6.18 exemplarily shows a comparison between experimental data and the modelling approach for a solid fraction of 33%. The model is able to predict the flow behaviour in a reasonable range. The main disagreement is observed for the jump downwards immediately after material preparation. This phenomenon can be discerned also for aluminium or tin–lead alloys but cannot be explained at the moment. Figure 6.17 Flow curve for liquid X210CrW12.
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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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Temperature (ºC) 1550 1500 1450 14
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100j 3 Material Aspects of Steel Th
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106j 4 Design of Al and Al-Li Alloy
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Page 155 and 156: 132j 4 Design of Al and Al-Li Alloy
Page 170 and 171: 5 Thermochemical Simulation of Phas
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Page 174 and 175: Figure 5.2 Calculated temperature v
Page 176 and 177: Figure 5.4 Composition profiles of
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Page 180 and 181: Figure 5.7 The density of X210CrW12
Page 182 and 183: 5.3 Calculations for the Bearing St
Page 184 and 185: Figure 5.11 Composition profiles of
Page 186 and 187: Figure 5.14 The density of 100Cr6.
Page 188 and 189: area which is available for heat tr
Page 190: Part Two Modelling the Flow Behavio
Page 193 and 194: 170j 6 Modelling the Flow Behaviour
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Page 244 and 245: 7 A Physical and Micromechanical Mo
Page 246 and 247: 3. Macroscopic averages or homogeni
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Page 250 and 251: and liquid are both assumed to be i
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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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