Twin-roll casting defects in light metals

Abstract

The twin-roll casting (TRC) of light metal alloys, in particular aluminium and magnesium alloys, represents a promising technology for the production of lightweight components thanks to its short process chain and promising combinations of properties. In the production of strip products, TRC is susceptible to a number of defects due to the coupled process steps of casting and forming, which prevent its use for more complex alloy combinations in the field. In this review, the defects in TRC of light metal alloys will be summarized and discussed. In addition to a basic classification of the defect types and definition of these, the formation mechanisms and avoidance strategies will be discussed. Special focus is placed on centreline segregation defects and surface bleeds, which occur in a large number of investigations in the literature. Effective avoidance strategies are defect-specific, but are mostly due to the combination of the plant design of the TRC process, the TRC parameters or the use of alloying elements to influence the solidification process.