Messung und Modelling des Einflusses von Schlichten auf den Waermeuebergang zwischen Schmelze/Gussstueck und Kokille beim Dauerformguss von Aluminium-Legierungen Abschlussbericht

At the computer aided simulation of the casting and solidification process of aluminium alloy shaped casting in metallic permanent moulds, the consideration of the heat transfer resistance 1/#alpha# and its influence on the solidification of the casting gains decisive meaning. The calculations should really result in quantitatively correct temperature fields in casting and mould. For this reason the non-stationary heat transfer resistance between melt/casting and mould was measured as a function of the solidification time, the interface temperature, the geometric conditions as well as the influence of coatings. Both heat flow density (q) as well as heat transfer coefficient (#alpha#) show a characteristic, time-dependent course. During gap formation #alpha# and q fall very quickly on subsequently constant values. A further decrease of #alpha# and q due to an assimilation of the boundary surface temperatures ensues not before solidification of the casting is finished. Moreover the results show, that the heat transfer resistance depends in a characteristic way on casting thickness, mould preheating temperature and particularly on the kind and condition of the coating. The consideration of the found relationships in a FEM simulation program leads to very good agreements between measured and calculated temporal temperature changes in casting and moulds, both in the semi-industrial laboratory scale as well as at actual component (engine blocks, brake housings). (orig.)Available from TIB Hannover: RN 9216(147)+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman