| 1. |
- Eck, Joakim, et al.
(författare)
-
Investigation of Pressure Distribution during Flow Regulation with a Stopper and Associated Mould Level Stability in a Continuous Cast-ing Simulator based on Liquid Metal
- 2022
-
Ingår i: La Metallurgia Italiana. - : Associazione Italiana di Metallurgia. - 0026-0843. ; 113:1, s. 42-51
-
Tidskriftsartikel (refereegranskat)abstract
- Stopper systems are widely used in the Continuous Casting (CC) process to control the steel flow from the tundish to the mould during casting of high-quality grades. The flow regulation region is subjected to severe under-pressures and generation of pressure fluctuations, especially around the narrowest gap and the tip of the stopper. This can lead to issues with air infiltration through the refractory materials, adverse flow regimes or even cavitation, which can lead to inclusions and level instabilities in the mould. Acquiring knowledge of such pressure distribution requires data from measurements which are difficult to conduct in the hostile high-temperature and corrosive environment of liquid steel in the plants.In this work, the pressure distribution is investigated in a Continuous Casting Simulator (CCS) based on a eutectic Bismuth-Tin alloy (Bi 58%-Sn 42%) with a low melting point (137 degrees C) equipped with a stainless-steel stopper rod. The pressure distribution is investigated through direct pressure measurements at two different points; a) Direct pressure measurement by sensor installed flush at the stopper-tip side and b) Indirect pressure measurements of back-pressure in the stopper argon line. The argon flow varied between 0 to 6 l/min, while casting speed varied between 0.6 to 1 m/min for a 1200 x 220 mm mould size.Results show that considerable under-pressures take place in the flow regulation region, reaching levels as low as 6.6 and 80 mbar absolute pressure at the stopper tip side and argon line. There was a detectable difference in pressure between the direct pressure measurements and additional argon line measurements. Ultimately, it could be concluded that the argon line pressure measurements; often used as industrial standard for ensuring positive pressures in the casting system, generally overpredicts the pressure in the system. This could lead to inappropriate argon settings for a caster, generation of unwanted inclusions and mould level instabilities. It was additionally possible to acoustically detect the onset of cavitation in the liquid metal.
|
|
| 2. |
- Jarfors, Anders E.W. 1963-, et al.
(författare)
-
Comparison between high-pressure die-cast and rheo-cast aluminium-SICp MMC; wear and friction behaviour
- 2021
-
Ingår i: La Metallurgia Italiana. - : Associazione Italiana di Metallurgia. - 0026-0843. ; :11-12, s. 13-18
-
Tidskriftsartikel (refereegranskat)abstract
- Aluminium is essential in automobile industry together with cast iron. Because of its lightweight property and good mechanical properties, aluminium reinforced with silicon carbide have found application as brake discs. Aluminium reinforced with 15%and 20% silicon carbide were high-pressure die-cast (HPDC) and Rheo-HPDC cast in the current paper. Micro-Vickers hardness and Rockwell C hardness showed different trends with the increasing amounts of SiCp-particles. Scratch resistance of the surface on micro-scale was analysed using a micro-scratch test to study the mechanics of the wear process. Reciprocating sliding wear of the composites was considered, using the HPDC cast aluminium with 20% silicon carbide of liquid casting as the sliding surface. The wear showed a combination of abrasive wear and adhesive wear. The metallography of the wear surfaces showed deep abrasive wear grooves. Wear debris from both the surfaces were forming a tribolayer. The formation of this layer decided the friction and wear performance as a result of the abrasive and adhesive wear mechanisms seen both in the micromechanics of the scratch test and in the friction behaviour.
|
|
| 3. |
- Lorenzon, A., et al.
(författare)
-
Application of Muon Radiography to Blast Furnaces : the BLEMAB project
- 2022
-
Ingår i: La Metallurgia Italiana. - : ASSOC ITALIANA METALLURGIA. - 0026-0843. ; :10, s. 62-68
-
Tidskriftsartikel (refereegranskat)abstract
- Muon radiography is a non-invasive imaging technique that exploits cosmic ray muons to explore the content of large, dense and otherwise inaccessible volumes. The European project BLEMAB (BLast furnace stack density Estimation through on-line Muon ABsorption measurements) represents an exemplary application of this technique in the industrial field: the aim of the project is indeed to investigate the capability of muon radiography to scan the inner part of active iron-making blast furnaces. In particular, the focus of the study is the characterization of the so-called "cohesive zone", which could be of great interest for steel-making companies. The project foresees the construction of a dedicated muon imaging detector, that will be installed at the blast furnaces in the ArcelorMittal site in Bremen (Germany). This paper describes the status of the project, including the development of software simulations and the manufacturing of the detector.
|
|
| 4. |
- Tarhouni, Ilef, et al.
(författare)
-
Evaluation of fracture toughness in HPDC aluminium alloys to estimate crashworthiness in automotive parts
- 2021
-
Ingår i: La Metallurgia Italiana. - : Associazione Italiana Di Metallurgia. - 0026-0843. ; :11-12, s. 60-66
-
Tidskriftsartikel (refereegranskat)abstract
- Aluminum high pressure die casting (HPDC) alloys are widely applied in the automotive sector. The constant needs for lightweight materials open a new opportunity for Al castings in structural applications in vehicles. New HPDC Al alloys with high ductility are available and are potential candidates for Body-in-White applications with crash requirements. Therefore, an assessment of the crashworthiness of these materials is required. In previous publications, the authors demonstrated that the fracture toughness, measured in the frame of fracture mechanics can be related to crash resistance in high strength steels and aluminum sheets. In this context, the characterization of the fracture toughness of two aluminum alloys with different ductility (AlMg4Fe2, AlMg4Fe2Zn3) was assessed following linear elastic fracture mechanics (LEFM), in terms of k icand elastic-plastic fracture mechanics (EPFM), in terms of the essential work of fracture, we. The results show that LEFM is not suitable to evaluate the fracture toughness of HPDC alloys with a significant amount of plasticity. On the other hand, it is showed that we describes the fracture toughness for high ductility alloys and it is here proposed as a material property to predict the crashworthiness of ductile HPDC alloys.
|
|
