Thermophysical Properties of Liquid Aluminum
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INTRODUCTION
ALUMINUM is a silvery-whitish light metal. It is the third most common element occurring in the crust of the earth. The world aluminum statistics reports, for March 2016, the production of 4856 metric tons of aluminum worldwide. Aluminum is used in all kinds of industries, ranging from cans for drinks and foils to wrap food, to the building industry for roofing and windows, to the automotive and aerospace industries, where it is used for lightweight structures. In production, aluminum is first melted and then undergoes different forming processes, such as casting, pressure die casting, and continuous casting. In current industrial practice, computer-based simulations allow modeling of casting, melting and remelting processes, heat transport, solidification shrinkage, residual stress, heat treatment, welding, forging, rolling, and cutting, or even predictions of microstructures. A key limitation to the successful introduction of these models is the lack of thermophysical data. Thus, experimentally obtained thermophysical properties of pure metals are of great importance as input parameters for various simulation tools and will lead to a better scientific understanding of
MATTHIAS LEITNER, THOMAS LEITNER, and GERNOT POTTLACHER are with the Institute of Experimental Physics, Graz University of Technology, NAWI Graz, Petersgasse 16, 8010, Graz, Austria. Contact e-mail: [email protected] ALEXANDER SCHMON is with the Patent Attorney Dipl.-Ing. Dr. Gernot Wirnsberger, Leoben, Austria. KIRMANJ AZIZ is with the EPCOS OHG a TDK Group Company, Deutschlandsberg, Austria. Manuscript submitted December 2, 2016. METALLURGICAL AND MATERIALS TRANSACTIONS A
liquid metals and alloys as well as help in the final production to reduce waste. Within this article, we will present a full set of experimentally obtained thermophysical properties of solid and liquid aluminum that can be used as input parameters for numerical simulations. The data presented are extensively compared to existing literature values and the range of experimental uncertainty is given for each property.
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EXPERIMENTAL PROCEDURE AND DATA REDUCTION
A. Ohmic Pulse-Heating Experiments High-purity aluminum wires (99.999 at. pct) with a diameter of 0.5 mm (Catalogue No. AL501115, Advent) were investigated using an ohmic pulse-heating technique. The details of the experimental pulse-heating setup have already been described extensively in References 1 through 3. The samples with about 60 mm length were treated with abrasive paper (grade 1200), cleaned with acetone, and subsequently resistively heated under N2 atmosphere at a pressure of 2.3 bar, starting at room temperature. A current pulse peaking at about 10 kA was discharged through the specimens and measured using an inductive coil (Model Number 3025, Pearson Electronics). At the same time, the voltage drop against common ground was measured using two Mo-foil voltage knives attached horizontally to the wire with subsequent voltage division. Due to the high heating rates of about 2 9 108 K s1 needed to a
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