Thixoforming : Semi-solid Metal Processing

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Figure 10.35 Experimental and simulated temperatures at middle and flange of the component after three cooling steps (ABAQUS). ing the narrow temperature interval of the thixoforming process, a preheated tool material with low heat conductivity would be preferred for the component regarding the material flow during the forming operation. Accordingly, heat losses could be minimized. Concerning the tool and its concept, a material with contrasting properties would be preferred to ensure lower temperature gradients of the dies for extending the tool life [23, 53, 54]. 10.5 Conclusion 10.5 Conclusionj405 Compared with the conventional route of drop forging, the process technology of forging metals in the semi-solid state shows potential with regard to the geometric complexity of the components, material savings and lower energy consumption of the required aggregates. Although the process requires only one forming step, it has an increased cycle time compared with the drop forging process because of solidification of the liquid-phase fraction. Efficient casting technologies are another strong competitor for the semi-solid forging technique in the area of aluminium components. Consequently, a possible niche for thixoforging production is not to be found in mass production but in special applications such as the described joining operations. However, analogous to thixocasting, adapted tool concepts have to be developed that ensure a higher durability, especially for economic thixoforging of steel components. The application of the rheo-route shows further savings potential. The expensive induction heating unit can be economized and the process can be shortened. The experiments show similar results to the thixoforging route. Numerical process modelling will be a helpful development tool by providing a deeper insight into metal flow and temperature field development.
406j 10 Thixoforging and Rheoforging of Steel and Aluminium Alloys List of Symbols and Abbreviations w circular frequency of the resonant circuit s Stefan–Boltzmann constant r density m magnetic permeability l heat conduction coefficient k electric conductivity e emissivity factor d penetration depth a ratio of ring side area to piston side area Wout measured temperature at the surface Win temperature at the middle of the billet We temperature of the environment Wdesired desired surface temperature _Fðr; tÞ volume power density Ak piston area Bv value flow gain ber(), bei() Kelvin functions CNC Computerized numerical control cp ^Ef specific heat capacity electric field FDM finite difference method FL load FR friction force ^Hz magnetic field strength Hsurrounding convective heat transmission ^Ic coil current peak value J0, J1 modified Bessel functions of first kind, zero and first order kf0 flow stress kv value dynamic gain Lc coil length Nc number of turns PID proportional–integral–derivative Pk i induced power in the scale i at the time step k. PLC programmable logic controller pN pressure Pv supply pressure R radius of coil Tsurrounding temperature of environment Ttool temperature of tools Tv time constant of the value TZM molybdenum-based alloy u(t) voltage v(t) velocity of the piston
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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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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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Page 432: steel billets into the semi-solid s
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Page 467 and 468: 444j Index arbitrary volume element
Page 469 and 470: 446j Index equilibrium tests 141 eq
Page 471 and 472: 448j Index - importance 273 ion flu
Page 473 and 474: 450j Index oxygen-sensitive element
Page 475 and 476: 452j Index - thixoforming 241 semi-
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Thixoforming : Semi-solid Metal Processing

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