| Résumé | Microstructures of as-cast 1060 and 380 (Al-9.2% Si-3.3% Cu) aluminum alloys made by a twin-rollcaster were determined. A cellular structure was found in 1060. In the case of 380 alloy a dendritic structure of αAlwas formed along with the eutectic Al-Si-Al2Cu in the interdendritique regions. The segregation in the 380 alloy shows thatthe central zone corresponds to higher microsegregation for the Al, Si, Cu and Fe with also the presence of microporosity. Thermal analysis was conducted on casting in a static horizontal mold and a solidification model has been devised for thecalculation of the heat transfer coefficient, which was found to be in the range of 1.6 - 2.0kW/m2·K·. The secondary dendrite arm spacing, λ, in 380 alloy shows a linearrelationship on a logarithmic scale with the distance from the wheel. By using the heat flow model, it was found that λis related to the local solidification time by the equation λ = 10.10 tf0·43. The value of theheat transfer coefficient for the strip casting of the aluminum alloys is around 9 KW/m2·K, which ismuch higher than in the static case. |
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