Improvement in quality of ingots from free-machining aluminium alloys by semicontinuous casting

Production of free-machining aluminium alloy ingots by continuous casting is related to nonuniform distribution of lead through ingot cross-section. Behaviour of liquid lead particles emerged in front of a growing dendrite and in the interdendritic space of solidifying metal, that appreciably influences their distribution in a solid ingot and, hence, quality of wrought aluminium alloys, has been investigated. Major forces affecting lead particles in the course of crystallization of an alloy are discussed and recommendations about optimization of lead inclusion sizes and their uniform distribution through thickness abd height of an ingot are offered.