INFLUENCE OF THE WORKING TECHNOLOGY ON Al-ALLOYS IN SEMI-SOLID STATE

We present two industrial technologies for working Al-alloys in the semi-solid state: thixocasting and rheocasting. The development of these processes has enabled significant progress and improved market competitiveness for the aluminium-casting industry. During both processes the share and the form of the globular solid phase are very important and they influence the flow of material in the tool. The comparison of thixocasting, rheocasting and the conventional casting process characteristics must be considered during the choice of one of these technologies. The performed investigations of rheocast components of A357 alloy revealed the important reasons for failures were the non-optimised parameters of the semi-solid working technology, the rapid opening of the tools and the non-optimised shape of the tool cavities.