Cast Shop Technology: Continuous Casting
Sponsored by: TMS Light Metals Division, TMS: Aluminum Committee
Program Organizers: Halldor Gudmundsson, Century - Nordural; Stephan Broek, Kensington Technology Inc
Wednesday 8:30 AM
March 22, 2023
Room: 31C
Location: SDCC
Session Chair: Halldor Gudmundsson, Nordural ehf
8:30 AM
TRC Combi Box - A Compact Inline Melt Treatment Unit for Continuous Casting: Margarita Gorsunova-Balkenhol1; Mark Badowski1; Marion Betzing2; Jan Stotz2; Ĝystein Pedersen3; 1Speira GmbH; 2Drache Umwelttechnik GmbH; 3Speira AS Karmĝy
An efficient inline melt treatment process is a key prerequisite for Aluminum producers to ensure compliance to today’s product requirements. Modern DC-casting lines use an equipment chain including Argon degassing, grain refiner addition and mechanical filtration to reduce hydrogen and non-metallic inclusions to low levels. Individual units of this process chain have been adapted to twin roll casting (TRC) conditions with low melt flow rates, long casting campaigns and high temperature sensitivity, while a holistic concept is pending. Speira and Drache initiated a project to develop a TRC degassing & filtration unit based on joint experience combining Argon degassing, CFF filtration and immersion heater temperature management into a user-friendly single box concept with small footprint and high metallurgical performance.This paper describes the technological approach for degassing, filtration and electrical heating, the integration into a single-unit concept and initial results of the pilot installation at Speira Karmĝy.
8:55 AM
CFD Modeling of Thin Sheet Product Using The Horizontal Single Belt Casting Method: Daniel Gonzalez Morales1; Mihaiela Isac1; Roderick Guthrie1; 1McGill Metals Processing Centre
The Horizontal Single Belt Casting (HSBC) process involves casting a thin “river” of molten metal directly onto a fast-moving, continuously cooled, endless belt. By casting at higher cooling rates than is common, uniform solidification rates across unconstrained “thin sheets” of melt are maintained, yielding excellent cast properties and microstructures. A non-isothermal analysis of heat flows in the critical region where the melt first pours onto the water-cooled belt is made and compared with results from an experimental caster. For this, the CFD ANSYS-Fluent 19.1 code was run, using various combinations of melt processing parameters. It provided accurate predictions of the “windows” available for stable strips of AA6111, AA5182, and AA2024 alloys, to be cast. The HSBC’s significant reductions in capital and operating costs, due to significantly reduced processing steps, lower energy consumption, and lower greenhouse gas emissions, make it a valuable alternative to current day practices.
9:20 AM
Numerical and Experimental Investigation of Twin-roll Casting of Aluminum-lithium Strips: Olexandr Grydin1; Kai-Uwe Garthe1; Xueyang Yuan1; Jette Broer2; Olaf Keßler2; Rostislav Králík3; Miroslav Cieslar3; Mirko Schaper1; 1Materials Science, Paderborn University; 2Materials Science, University of Rostock; 3Physics of Materials, Charles University
The main disadvantage of Al-Li alloys is an anisotropic behavior combined with limited formability. As conventional processes reach their limits, the formability of Al-Li alloys is to be improved by means of twin-roll casting. Twin-roll casting is an efficient process for the production of thin strips. The characteristic of this process is the combination of solidification and plastic deformation in a single unit. In this study, the twin-roll casting of Al-Li alloy using copper shells was represented by a numerical simulation through a thermofluid model implemented in ANSYS-Fluent. This simulation-based study aims to investigate the influence of casting speed, casting temperature, strip thickness, and length of strip forming zone on strip outlet temperature and a specific length of deformation zone, thus optimizing the practical manufacturing process. The parameters determined by means of the simulation were used for the manufacture of strips and the microstructure was analyzed on their basis.
9:45 AM
Segregation Mechanisms and Their Effects on the Aluminium Flat Rolled Products (Sheet/Foil) Produced by Twin Roll Casting Tech: Onur Birbasar1; Feyza Denizli1; Eda Özkaya1; Samet Sevinç1; Ali Ulus1; Canan İnel1; 1Asas Alüminyum San. ve Tic. A.S.
TRC technology having significantly higher solidification rates compared with the conventional casting methods. As-cast sheet microstructure produced with TRC exhibits supersaturated region of alloying elements near the surface and the centreline segregation at the mid-plane of the as-cast material. Surface and edge segregations also can be seen in as cast materials. These segregations can have different effects on the final material properties in terms of the mechanical properties, corrosion properties, number of pinholes and rolling performance. It becomes extremely important to eliminate or reduce the intensity of the segregations. In this study, the formation mechanisms and the parameters for minimizing of centreline segregation in 8xxx series aluminium foil alloy casted with steel-steel and copper-copper shell pairs were examined. Also, surface and edge segregations were studied. As-cast samples were prepared metallographically and investigated by using light microscope, scanning electron microscope equipped with EDS. Electrical conductivity measurements were also performed.
10:10 AM Break
10:25 AM
Novel Methods for Roll Texturing: EDT and Sandblast Applications for Aluminum Twin Roll Cast and Cold Rolling: Yusuf Ozcetin1; Onur Birbasar1; Ali Ulus1; Koray Dündar1; Feyza Denizli1; Canan İnel1; 1ASAS Aluminum I. Company
In twin roll continuous casting(TRC) and aluminum cold rolling; rolls are conventionally roughened by grinding. However, this method may cause defects on the surface of the final sheet product. Structures called “shingles” are formed due to the nature of the TRC method. Because of the shingles, aluminum debris(SMUT) is carried on the sheet surface during the manufacturing processes. With the sandblasting, the surfaces of the rollers are roughened in a different topography, unlike the mill finish texture. Thanks to this topography, the shingle formation mechanism is prevented. In addition, thanks to the EDT process applied to the cold rolling rolls; by obtaining a crater-like topography, the defective shingle structure from the casting is tried to be eliminated. In this study; sandblasting of casting rolls; on the other hand, both sandblasting and EDT processes were applied separately to cold rolling rolls. The obtained results were evaluated by using surface characterization methods.
10:50 AM
Characterization of 8006 Aluminium Alloy Casted by TRC Technology with Steel-steel and Copper-copper Roll Pairs: Feyza Denizli1; Onur Birbasar1; Koray Dündar1; Ali Ulus1; Canan İnel1; Yusuf Özçetin1; 1Asas Aluminyum
Aluminium alloys are widely used in many application areas due to the properties of high thermal conductivity, good formability, high corrosion resistance and recyclability. Growing demand for aluminium materials leads the aluminium manufacturer to increase the casting productivity. One of the effective way to increase the casting speed in twin roll casting (TRC) is changing the cooling conditions required for solidification. Shell which is the component of cast roll contacts with molten metal ensures solidification by removing the heat from molten metal. Depending on the thermal conductivity of shell material, casting speed and productivity can be increased. However, casting microstructure and other properties of the material can change because of the solidification conditions. In this study, 8006 alloy is casted by TRC method using copper-copper roll pairs as an alternative to convetional steel-steel pairs. Microstructural analysis, electrical conductivity measurements and mechanical properties were investigated comparing with steel-steel casted material.
11:15 AM
Tailoring the As-cast Microstructure of Twin-roll Cast AA3105 Alloy Produced by St/Cu Shell Pair: Cemil Isıksacan1; Mert Gülver1; Hikmet Kayacetin1; Onur Meydanoglu1; Erdem Atar2; 1Assan Aluminum; 2Gebze Technical University
Extracting the heat from the liquid metal with the help of the water-cooled caster rolls(designed with core and shrink-fitted shell)and then reaching as-cast strip in various thickness with different casting speed generates the phenomena of the twin roll casting process.In order to increase productivity (combination of the casting speed and as-cast strip thickness) which is one of the most important output of the TRC, different shell materials having different heat transfer coefficient rate could be used. In case of using St/Cu (Steel-Copper) shell pair,higher productivity rate could be obtained. However, as-cast microstructure of the materials could have some differences such as behavior of the center line segregation and grain structure compared to the sample produced by St/St shell pair. In this study, casting parameters (set-back, roll speed, strip speed & thickness) are changed in order to observe the differences such as centerline segregation and grain structure close to the surfaces.