Thixoforming : Semi-solid Metal Processing

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Figure 6.8 Experimental results exhibit a quasi-stationary flow in pressure–time curve although a downward drift is observable for the first sensor located near the ingate. (mean velocity of the slurry u ¼ 6ms 1 ). 6.1 Empirical Analysis of the Flow Behaviourj179 one pressure sensor and the effective plunger pressure, a quasi-stationary flow is assumed, although a downward drift is observable in the pressure–time curve for the first sensor located close to the ingate system (Figure 6.8). 6.1.5.4 Horizontal Capillary Rheometer Since the operating temperature of the vertical capillary viscometer is limited to a maximum temperature of 250 C, the experimental setup is not appropriate for rheological measurements of semi-solid alloys with an excessive solidus–liquidus interval. A horizontal capillary viscometer has been designed particularly for rheological measurements of higher melting alloys such as aluminium and magnesium. The application of electric heating cartridges ensures significantly higher operating temperatures of up to 650 C while special attention is paid to the heat balance of the tool assembly. The modular design of the viscometer in combination with the design, position and power dimensioning of the electric heating system ensures a continuous flow of the material under investigation through the capillary without solidification occurring during the experiment, and also short setup times through a simple assembly. Compared with the vertical viscometer tendencies of time-dependent viscosity behaviour can be detected with the installation of several sensors over the flow length (Figure 6.9). Based on the design experience and the thermal requirements, especially the design of the measurement system had to be changed. Quartz sensors, directly mounted on the capillary surface, are in common use in pressure die casting. For sensitivity reasons, these sensors are replaced with highly sensitive force sensors. Because the operating temperature is limited to a maximum of 250 C, the sensors are mounted in a water-cooled rack on top of the tool assembly. They are connected to the capillary surface with pins of a specific diameter for load transmission (Figure 6.10). In order to detect time dependency in the rheological behaviour, the capillary is equipped with four pressure sensors in an equidistant arrangement over the flow length. If time dependency occurs, the sensors will detect a non-linear
180j 6 Modelling the Flow Behaviour of Semi-solid Metal Alloys Figure 6.9 Illustration of the horizontal capillary viscometer designed to study the rheological behaviour of higher melting alloys (aluminium, magnesium) and to detect tendencies in timedependent rheological behaviour. pressure drop with the measuring length. The entire experimental setup of the horizontal capillary viscometer is shown in Figure 6.11 and results are presented in Figure 6.12 for a flow velocity of 3.55 m s 1 . The indirect force measurement system has turned out to be a weak point, likely to reduce the performance of the experiment significantly. A sufficient impermeability is required with excellent tribological performance at the same time. Most of the evaluated material combinations could not provide sufficient impermeability due to drilling tolerances or non uniform heat expansion. When performing an experiment, either the system failed in terms of friction or the semi-solid metal infiltrated the still existing gap and blocked the load transmission system as it solidified. Several Figure 6.10 Schematic illustration of the indirect force measurement system. Highly sensitive force sensors are mounted outside the capillary tool. Flow pressure is transmitted by either monolithic or assembled pins.
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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 151 and 152: 128j 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
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Page 244 and 245: 7 A Physical and Micromechanical Mo
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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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