Cast Shop Technology: Continuous Strip Casting
Sponsored by: TMS Light Metals Division, TMS: Aluminum Committee
Program Organizers: David Gildemeister, Arconic Technology Center
Monday 2:00 PM
February 27, 2017
Location: San Diego Convention Ctr
Session Chair: Kai-Friedrich Karhausen, Hydro Aluminium Rolled Products GmbH; Murat Dundar, Assan Aluminium
2:00 PM Introductory Comments
Effect of Grain Refiners on Aluminum Twin Roll Casting Process: Yu Matsui1; Koichi Takahashi1; 1UACJ Corporation
The purpose of this study is to investigate the effect of adding the Al-Ti-B grain refiner to the aluminum twin roll casting. The authors analyzed the microstructure of the as-cast strip produced by the twin roll casting based on several casting conditions. The results showed that the amount of the TiB2 particles and the temperature gradient in the solidification area are the key factors for enhancing the effect of the grain refining. Additionally, this study simulated the behavior of the TiB2 particles in the aluminum melt. The temperature distribution of the aluminum between the twin rolls was also calculated. The authors clarified the relationship between the grain refiner particles and the temperature gradient for the grain refining effect during the twin roll casting.
Influence of Process Conditions on Segregation Behavior in Twin-Roll Casting of an AlFeSi Alloy: Christian Schmidt1; Dag Mortensen2; Kai Karhausen1; 1Hydro Aluminium Rolled Products GmbH; 2Institute for Energy Technology
In twin-roll casting of aluminium the content of alloying elements is limited due to the formation of segregations mainly at the centerline and the surface of the strip. Their appearance, size and localization have a major influence on the final product quality. AlFeSi alloys are well suited for this investigation as they are alloyed with iron far beyond solubility. In casting experiments, casting speed is altered stepwise while all other casting parameters are not actively changed. Naturally roll and strip temperatures are increasing while separation force and strip thickness are reducing when casting speed is increased. Basically with increased casting speed the liquid and semi-solid sump is growing and contact time of the strip with the water-cooled roll is reduced. Hence both factors influencing segregation behavior, namely solidification conditions and deformation of the sump, are changing during the experiments. Experimental investigation is supported by process simulation in Alsim.
Effect of Magnesium Content on Microstructure and Mechanical Properties of Twin-Roll Cast Aluminum Alloys: Onur Meydanoglu1; Cemil Işıksaçan1; Hatice Mollaoğlu Altuner1; Mert Günyüz1; Onur Birbaşar1; 1Assan Alüminyum San. Tic. AŞ
High magnesium containing aluminum alloys are preferred in applications where high strength and good formability are of importance. However, enhanced Mg content in AlMg alloys leads to increased solidification range which makes these systems difficult to be produced by twin-roll casting. In this study, AlMg alloys were produced by twin-roll casting with different Mg contents up to 5.2 wt. % and processed to obtain soft annealed 1 mm thick samples. The effect of Mg content on the microstructural evolution during twin-roll casting as well as downstream processes and mechanical properties of soft annealed 1 mm thick samples was investigated. Addition of Mg leads to coarser grain structure in as-cast strips and finer grain structure after intermediate annealing as well as soft final annealing. At the same time, enhanced Mg content provides higher yield and tensile strengths as well as lower elongation.
3:20 PM Break
Influence of Sticking on the Roll Topography at Twin-roll Casting of Aluminum Alloys: Olexandr Grydin1; Florian Nürnberger2; Mirko Schaper1; 1University of Paderborn; 2Leibniz Universität Hannover
The formation of strips at twin-roll casting depends on the state of the roll surface. The processing conditions, which are characterized by high metal-tool interface temperatures and compression stresses, provoke sticking between the cast material and the rolls. This effects changing of the tool’s topography, impairment of the strip’s surface quality and interference of its flatness. In the scope of this study the evolution of roll’s topography at twin-roll casting of 3 mm thick strips of aluminum alloys EN AW-1070 and EN AW-6082 without any release agents was experimentally analyzed using laboratory casting unit. The effect of repetitive tool’s self-cleaning during processing of the EN AW-6082 alloy was observed, whereas aluminum of technical purity showed intensive sticking on the roll surface. In the last case micro-profiling of the tool’s surface is not more efficient and release agents have to be used for improvement of the strip’s formation conditions.
Material Surface Roughness Change in Twin Roll Casting of Aluminium as Cast Sheet Product: Ali Ulus1; Ceyhun Kuru1; Özgür Özşahin1; Sadık Kaan İpek1; Eda Dağdelen1; 1Teknik Aluminium
Continuous casting of aluminum sheet products has so many advantages due to its short production route. These advantages can be listed as low production cost, low investment cost and short delivery time. However, this method has some technical insufficiencies that are mostly related with quality issues. These disadvantages can be listed as low alloy range, mechanical properties and surface quality. The most critical issue is surface quality. To improve casted sheet surface quality, cold mill performance of continuous cast coils and final surface properties; some operational applications are needed to guarantee for a sustainable process parameters and repeatable measuring method. With this work, it is aimed to evaluate the surface quality in terms of surface roughness changes with casting and cold rolling operations. Besides material’s roughness, change in casting shell and work roll roughness, in-going material roughness and planning parameters of casting and cold rolling operations are involved.
Twin-roll Casting of Aluminum-steel Clad Strips: Static and Dynamic Mechanical Properties of the Composite: Mykhailo Stolbchenko1; Olexandr Grydin1; Mirko Schaper1; 1Paderborn University
The manufacturing of thin aluminium-steel clad strips by means of twin-roll casting is a prospective trend of the progress in the light metals sheet production. The resulting composite possesses high bonding strengths due to the presence of a continuous thin layer of intermetallic phases at the bonding interface of metallic constituents. At the same time, for the application of twin-roll cast clads, the evaluation of their properties is of great importance. In order to determine the behavior of twin-roll cast aluminum-steel clad strips under loading, quasi-static monotonic and high-cycle fatigue tests were carried out. Therefore, strips in the as-cast state as well as after a heat treatment, stimulating the growth of the intermetallic phases, were subject for the characterization. In addition, the specimen’s fracture surfaces were analyzed by using scanning electron microscopy to obtain information on the type of fracture, the location and source of the crack nuclei.