LOCAL SQUEEZING CASTING INFLUENCE ON THE COMPACTNESS OF AlSi10Mg ALLOY CASTINGS

Casting solidification brings to the shrinkage in the liquid state, solidification shrinkage and shrinkage in the solid state. Recently, technologies of die and gravity casting have increased the number of highly functional castings, which have been characterized with the very complex geometry. due to the different wall thickness in these castings, as well as the high solidification rates, premature interruption of feeding occurs. Impossibility of adequate feeding results in occurring of stand-alone solidification areas. These areas have been characterized with the smallest cooling and solidification rate and with the volume defects such as shrinkage, microand macro porosity appearance. The aim of the local squeezing casting process examination has been to eliminate the hot spot i.e. the place of potential formation of shrinkage porosity. The influence of variation of process parameters on the density i.e. soundness (compactness) of AlSi10Mg alloy castings has been obtained by the local squeezing process with the pin during gravity casting in the special permanent mould. Local squeezing parameters have been determined on the basis of preliminary investigations of AlSi10Mg alloy: temperature intervals and relevant temperature of singular phases precipitation and the microstructure development at different cooling rates. The temperature interval of performing the local squeezing casting process have been established in which the density values approaching to the theoretic ones have been determined.