Thixoforming : Semi-solid Metal Processing

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Figure 3.48 Determined contents of magnetic phase (ferrite) as a function of the annealing time for ageing temperatures of 490, 540 and 595 C. 1270 C/30 min/air are considered. Figure 3.49 depicts the hardness curve of the samples held isothermally at 400 and 450 C. It is apparent that the hardness values decrease with increasing temperature, the conventionally hardened material exhibiting a considerably steeper decrease than the thixo-material. Due to the seemingly very stable structure, this material exhibits constant values of more than 58 HRC at a Figure 3.49 Hardness curves for conventionally hardened and of thixoformed steel X210CrW12 under long-term annealing. 3.6 Microstructure Analysis and Material Propertiesj97
98j 3 Material Aspects of Steel <strong>Thixoforming</strong> temperature of 400 C and a holding time of 1000 h, whereas the conventionally hardened material decreases to values below 53 HRC. At a fictional service temperature of 450 C, the difference between the two states becomes even more pronounced, because the conventionally hardened material exhibits at this temperature already a very steep decline below 53 HRC after 100 h. In conclusion, it can be noted that by means of the application of an adjusted heattreatment strategy, the insertion temperature of the cold working steel X210CrW12 could be increased considerably and could even be inserted at temperatures at which usually only warm-working steel is used. Depending on the particular application, service temperatures of up to 400–450 C seem realistic. 3.6.2 Structural Changes and the Properties of the Hypo-eutectic Steel 100Cr6 Due to the chromium and carbon concentrations, the austenite has an Ms temperature of about 350 C, so that it transforms into martensite during quenching. The structural images in Figure 3.50 confirm the calculations and reveal a martensitic structure, at which a light seam is located at the former austenite–grain boundaries. By close examination of the element distribution images and the line-scan of the microprobe examinations, it can be assumed that the white phase is a two-phase structure of retained austenite with finely ingrained carbides, which could be confirmed by microhardness measurements [70]. Future research should deal with the systematic observation of the structural development of steel 100Cr6 without a connected carbide network. The transformation behaviours of both the <strong>solid</strong> and liquid phases have to be considered to be able finally to derive a heat-treatment strategy that delivers useful mechanical properties based on the partial liquid state. In addition, the volume shrinkage and the concurring pore formation for steel 100Cr6 will be an important factor for the mechanical properties. 3.6.3 Final Evaluation of the Heat-treatment Strategies The SSM potential of steel concerning the metallic properties was examined by means of systematic heat treatments on steels X210CrW12 and 100Cr6. After processing in the partial liquid state, new structures could be produced by means of isothermal Figure 3.50 Microstructure of 100Cr6 specimens quenched from 1350, 1375, 1400 and 1425 C.
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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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5 Thermochemical Simulation of Phas
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here it can be assumed that the dat
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Figure 5.2 Calculated temperature v
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Figure 5.4 Composition profiles of
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It is clear that C has by far the s
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Figure 5.7 The density of X210CrW12
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5.3 Calculations for the Bearing St
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Figure 5.11 Composition profiles of
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Figure 5.14 The density of 100Cr6.
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area which is available for heat tr
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Part Two Modelling the Flow Behavio
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170j 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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