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  • 1
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 141-143 (July 2008), p. 213-218 
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Notes: The deformation process of steel in the semi-solid state, or thixoforming is an alternativesolution to the classical industrial processes that are the casting or the hot forging.Thixoformed steel parts are of better quality and may substitute advantageously parts realized incast iron leading to an improvement of the rigidity, for example, but also parts in aluminium alloysobtained by the main deformation processes: for lower volume, thixoformed steel parts, keeping thesame functionality, present superior mechanical properties than the parts realized in aluminiumalloys. The industrial development of the steel thixoforming must be accompanied by theknowledge and the various parameters control of the process: steel grades definition andelaboration, the homogeneous high-temperature heating of the slug before deformation, conceptionor re-conception of the part to adapt it to the process and the practice properties, the equipmentdefinitions which are used for the deformation operation at the semi-solid state. The handlingsystem is also important in the thixoforming process; it is going to allow the slug transfer, at thesemi-solid state, between the heating zone and the tooling or to evacuate the thixoformed parttowards the mean assuring the quality heat treatment of the part. The means choice which areindustrially going to ensure the process have a big importance to obtain successful production lineand so, a cost reduction by “finished” part competitive with regard to processes used classicallytoday. After the description of the applicable key points to the main parameters and the solutionsused to obtain a successful product: high mechanical characteristics, near net shape or net shapegeometry, no flash and limited machining operation, ... are described , The investigations finishedwith an approach comparing the part cost realised by thixoforming process with regard to classicalprocesses
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 141-143 (July 2008), p. 207-212 
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Notes: The development of the thixoforming process made great progress since its beginning.But whereas thixoforming of aluminium and other low melting point alloys is now an industrialreality, thixoforming of high melting point alloys, as steel, is still at the research level. Hightemperature issues, die wearing and production rate are problems that must be solved and are moreand more investigated. This work is a study of the robustness of a complete thixoforming unitdealing with steel. This flexible unit allows parts of various shapes be formed in conditions close toindustrial ones. The study focus on the heating strategy, heat exchanges between the slug and thetool, the feeding and the cycle time. In this work, modelling has been used to simulate heating andfeeding. In parallel, experiments have been made to obtain the needed parameters, to validate themodelling and to evaluate the capacities of such a line
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 141-143 (July 2008), p. 659-664 
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Notes: Thixo-extrusion processing could become an important technique to extend the range andcomplexity of extruded profiles. This work presents the results of thixo-extrusion process appliedon aluminium alloy and they were carried out with both computer numerical simulation andexperimental methods. The thixo-extrusion set-up was made. Backward extrusion tests wereparticularly studied and simulated using Forge 2005 software. The constitutive equation used forthese simulations is based on a micro-macro model for the semi-solid evolution. The constitutiveequation parameters were identified due to comparisons of the simulated load-displacementresponses with experimental ones for backward extrusion tests on 7075 semi-solid aluminium alloy,for different temperatures
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 141-143 (July 2008), p. 689-694 
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Notes: The pre and post treatment of the thixoformed parts in terms of heating conditions andcontrolled cooling has a great influence on the final microstructure and the properties of the partsand their homogenization. The paper presents recent investigations on metallographic analysis andhardness measurements on as thixoformed parts and post treated ones. For these tests, different steelgrades are investigated and the liquid fraction of the slug before deformation is evaluated to 30 %
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Notes: Steel thixoforging process combines the advantages of performing parts having highlycomplex shapes and good mechanical properties. These advantages result from the shear thinningflow behaviour of semi-solids due to microstructure changes during the material deformation. Manyparameters such as steel grade, raw speed, slug temperature, tool temperature influence the steelthixoforging process. In this work, we are interested in analysing the influence of thermalconditions as well as ram speed on the flow behaviour and the microstructure of the final parts. Todo so, thixo-extrusion tests on a high speed hydraulic press were performed on C38 steels usingdifferent ram speeds and different temperatures for the tools. The temperature is measured in the dieclose to the tool-material interface during the whole process. Correlations between the temperaturemeasurements, the flow profile and the microstructure are discussed. Using the Finite Element codeForge2005, these thixo-extrusion tests are simulated. Using an inverse method, some parametersused in the thermal exchange modelling are identified by successive comparisons betweencalculated and measured temperatures within the die
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 116-117 (Oct. 2006), p. 721-724 
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Notes: This paper presents experimental results on steel thixoforming. The influence of thermaleffects on the semi-solid response is analysed through the influence of thermal exchanges with toolsand environment. Several rheological experiments such as compression, extrusion or radial fillingtest were developed to understand the semi-solid steel behaviour and determine the parameters thathave a major influence on thixoforming. Actually, in our experiments, the temperature of the slugand consequently the solid fraction were found first order parameters while; the morphology of thesolid phase plays a minor role
    Type of Medium: Electronic Resource
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