Simulationsgestützte Entwicklung eines Gießverfahrens zur Herstellung von Schichtverbunden aus Aluminiumlegierungen

Translated title of the contribution: Simulation-based development of a casting process to produce clad aluminum strips

Stefan Heugenhauser

Research output: ThesisDoctoral Thesis

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Abstract

The combination of two different aluminum alloys with different chemical, mechanical and physical properties allows the production of compounds with entirely new characteristics. Rising demands on the efficiency and specificity of strip-shaped clad materials require the replacement of classic compound alloys by high-strength, high performance alloys. However, with these materials with reduced plasticity the conventional roll bonding process reaches its limits and alternative processing routes have to be developed. One promising way is represented by the compound casting method in which liquid melt is cast onto a preheated substrate plate in order to form a metallurgical bond at the interface. To investigate this approach, a small-scale pilot plant for the casting of pure aluminum (Al99.8) on different substrate plates (Al7075, AlSn25) under defined processing conditions was developed. With that, the compound casting process of selected material combinations with varying casting parameters such as the thickness ratio of the compound layers, the temperature of the substrate layer and the clad melt, the texture of the substrate surface as well as the casting speed on the metallographic quality of the casted compounds can be investigated. The temperatures at the interface between the substrate and the clad alloy are not accessible by direct measurement. Therefore dynamic and static two-dimensional and three-dimensional numerical simulation models were set up and iteratively calibrated using measured temperatures obtained from various casting experiments. With these models, the thermal conditions at the interfacial layer between the substrate and the clad alloy as well as the occurring remelting and solidification processes during the compound formation over the entire cross section of the compound material can be calculated in very high temporal and spatial resolution. All thermophysical data of the substrate alloys that are necessary for a precise numerical simulation were measured from room temperature up to a liquid state. The examination of the casting experiments have shown that the oxide skin at the surface of the substrate plays a critical role for the successful formation of a metallurgical compound. To firmly bond the substrate with the initially liquid aluminum layer, its detachment and removal from the compound interface during the casting process is indispensable. The combination of the numerical calculations with the results from the casting experiments finally permits to correlate the thermal conditions at the interface with the debonding of the oxide layer at the substrate surface and further to predict the compound quality of as-cast plates.
Translated title of the contributionSimulation-based development of a casting process to produce clad aluminum strips
Original languageGerman
QualificationDr.mont.
Awarding Institution
  • Montanuniversität
Supervisors/Advisors
  • Schumacher, Peter, Assessor A (internal)
  • Volk, Wolfram, Assessor B (external), External person
Publication statusPublished - 2018

Bibliographical note

embargoed until null

Keywords

  • compound casting
  • metallurgical compound
  • aluminium alloys
  • oxide layer
  • small-scale pilot plant
  • numerical process simulation
  • thermophysical properties

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