Sponsored by: LMD Aluminum Committee
Program Organizer: Julian V. Copenhaver, Technical/Quality Manager, NSA A Division of Southwire, PO Box 500, Hawesville, KY 42348
Monday, AM Room: A10
February 5, 1996 Location: Anaheim Convention Center
Session Chairperson: Mr. Edmund J. Elder, Alumax of South Carolina, P. O. Box 1000, Goose Creek, SC 29445
COMPARATIVE SAMPLING MOLDS EVALUATION: Laura Pierrard, Research Engineer, Phillippe Jarry, Jean Charbonnier, Pechiney Centre de Recherches de Voreppe, BP 27, 38340 Voreppe, France; Colette Rigaut, Aluminium Pechiney Division Alliages de Moulage, BP 7, 38340 Voreppe, France
The metallurgical industry needs to cast alloys with narrow tolerances in their chemical composition in order to reduce variability of their use properties. Therefore, appropriate sampling practices and analytical methods are required. Both accuracy and precision of the analytical results are limited by the non-homogeneity of as cast-disk or cylinder samples, which results from macrosegregation phenomenon. This paper presents a comparison between Pechiney and other commonly used molds (ASTM designation: center-pour molds type B and vacuum mold). Two complementary approaches are exhibited for the different molds designs: Solidification modelling in order to predict macrosegregation localization using the Simulor software; Experimental characterizations. Radial and axial segregation profiles are determined by Analytical Scanning Electron Microscopy as well as analytical precision evaluation by spark emission and X-ray fluorescence spectrometries for a given cutting depth.
DEVELOPMENT OF A SINGLE WHEEL, HIGH SPEED ALUMINUM STRIP CASTER: Lawrence D. Ray, Reynolds Metals Company, PO Box 27003, Richmond, VA 23261; George A. Sloan, Reynolds Metals Company, PO Box 1155, Hot Spring, AK 71901
The aluminum industry has been in search of a viable continuous casting process for many years. Such a process would provide an increase in production as well as lower production costs. The melt drag process is capable of producing thin aluminum sheet at extremely high casting rates. Over the past ten years, many milestones have been reached in making this process acceptable for use in production. Some of these accomplishments are reviewed in this paper along with a general overview of some of the technical aspects of melt drag casting. In addition, a comparison is made with other processes available for continuously casting aluminum slab and strip.
PROCESS AUTOMATION FOR HIGH-SPEED-THIN-GAUGE-TWIN ROLL CASTING TECHNOLOGY: Klaus Peter Maiwald, Bruno Mariéthoz, Lauener Engineering, Stationsstrasse 21B, CH-3645 Gwatt, Switzerland
The successful Joint Venture development between Lauener-Engineering and Hydro-Aluminium in respect to thin gauge - high-speed - casting demanded a highly sophisticated Process-Control System. The targets of 100% (and above) Productivity increases and gauges of 2 mm and below within tolerances of +/-1% and below where reached on time. The paper will explore details of the Process Control system applied from furnace to Caster and Coiler.
MOLTEN ALUMINIUM: RECENT ADVANCES IN WEIGHING AND TRANSPORTATION: Palmi Stefansson, Technical Manager, Hydro Equipment AS, P. O. Box 80, N-1321 Stabekk, Norway; Ole Ingar Vee, General Manager, Procon a/s, Kronvegen 3B, N-1265 Oslo, Norway; Dr. Thorsteinn I. Sigfusson, Science Institute, Austurbrun 17, IS-104 Reykjavik, Iceland
Transportation of liquid metal is an important aspect of the efficiency of any aluminium smelter operation. The paper discusses a tapping method developed by Hydro Aluminium which has proven superior to the conventional crane or forklift tapping of potroom metal. The overall manning can be halved by the extensive rationalization of this method. The remote computer operated control of metal mass transfer by electronic scales mounted on the tapping vehicle is explained. As the system uses no skimming, the dross generation and sodium content of metal is shown with collected data. The impact and advantages of this novel engineering on the casthouse are finally explained and discussed in detail.
MELT FLOW IN SPOUT/STOPPER SYSTEMS AND ITS IMPACT ON METAL QUALITY IN ALUMINIUM CASTHOUSES: C. J. Moritz, Dr. Wolfgang Schneider, H. P. Krug, V.A.W. Aluminium AG, Research and Development, Georg-von-Boeselager-Strasse 25, D-53117 Bonn, Germany
In aluminium casthouses spout/stopper systems of different designs are in operation for regulation of the melt flow during transport of the melt for example, from a launder into a D.C. casting mould, from a launder to another launder, or from a launder into a casting ladle of an ingot casting carousel. Due to the different designs, variable and high melt flow rates in the system occur. This leads to the formation of significant under-pressures which cause turbulences, and as a result of this, a pollution of the melt with inclusions. The under-pressure courses in different spout/stopper systems will be described and discussed and their impact on inclusion content reported, investigated by LiMCA measurements.
10:10 am BREAK
BENEFITS OF MASTER ALLOY MELT TREATMENTS IN THE ALUMINIUM FOUNDRY INDUSTRY: P. S. Cooper, R. Cook, Dr. M. A. Kearns, London & Scandinavian Metallurgical Co. Limited, Fullerton Road, Rotherham, South Yorkshire, S60 1DL, England
The general benefits of the master alloy approach to foundry melt treatment in terms of environmental and technical advantages are reported. New data on the environmental impact of master alloy treatments compared with other addition methods are provided. New application areas for melt treatment are described with reference to Sr in high pressure die castings. The results of a controlled trial on A380 alloy are presented and it is shown that Sr offers benefits in terms of the consistency of casting properties. Sr modifies the microstructure, particularly of thicker section castings and virtually removes gross porosity. The paper concludes with a field study showing the technical benefits of TiBAl grain refinement compared with other methods of refining Al-Si sand castings.
LOW-NOx OXY-FUEL FLAMES FOR UNIFORM HEAT TRANSFER: Dr. Loo Tjay Yap, The BOC Group Technical Center, 100 Mountain Avenue, Murray Hill, NJ 07974; Mohammed Pourkashanian, University of Leeds, Department of Fuel and Energy, Leeds LS2 9JT, UK
Flame characteristics such as controllable heat-transfer rates and NOx formation rates have been optimized for a novel self-cooling oxy-fuel burner using CFD techniques. Contrary to traditional axisymmetric flames, here, luminous large aspect-ratio flames are established resulting in uniform heat transfer rates. Extreme flame stability allows a wide operating range with low noise emissions. Luminosity provides effective flame cooling as well as dampening of turbulent fluctuations resulting in reduced NOx formation rates. Computational modeling has been verified with physical probing as well as in-situ Laser Induced Fluorescence (LIF) measurements of OH. Increased thermal efficiencies, improved productivities, unaffected metal yields, lower costs, and decreased NOx emissions are demonstrated in commercial aluminum furnaces.
CORROSION OF REFRACTORIES AT THE BELLYBAND OF ALUMINUM HOLDING AND MELTING FURNACES: Sylvio Quesnel, S. Afshar, C. Allaire, CIREP-CRNF, École Polytechnique, Metallurgy and Materials Engineering Department, 8475 Christophe-Colomb Road, Montréal, Québec, Canada H2M 2N9
Different phenomena leading to the degradation of the refractory lining at the bellyband of aluminum holding and melting furnaces are described. The effect of temperature, alloy composition, fluxing agent, and surrounding atmosphere, on the corrosion of aluminosilicate refractories in such applications has been studied. A laboratory test that simulates the conditions at the bellyband in the above furnaces was developed. Results suggest that sidewall build-up originates from corundum formation at the surface of the molten metal, which then grows inside the refractory above the metal line.
PRIMITIVE PRACTICES IN TODAY'S CAST SHOPS (IS YOURS ONE OF THEM?): George J. Binczewski, S.C. Systems, PO Box 6154, Moraga, CA 94570
The continuing evolution of the aluminum industry cast shop has involved the
introduction of many production operations which were quite innovative and
considered important for their time. Too often, the original reasons for them
have become obscured, and the result is the perpetuation of daily practices
which have become inefficient, cost, and open to technological scrutiny and
challenge. Current practices are identified and appropriate remedies are
suggested concerning grain refining, filtration, furnace practices, skimming,
casting, alloying, sampling, and quality control.
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