Influence of Process Conditions on Segregation Behavior in Twin-Roll Casting of an AlFeSi-Alloy

摘要

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.