EVALUATION OF POROSITY OF ALZN5MG CASTINGS MADE BY SQUEEZE CASTING TECHNOLOGY

Abstract

The paper shows the results of research aimed to assess the impact of high squeeze pressure on the porosity of
AlZn5Mg alloy castings, including its distribution in slab-type castings with dimensions of 25 x 100 x 200 mm. The
research was carried out on castings made by two methods: squeeze casting and gravity casting. The pressing
was conducted at a pressure of 100 MPa at an initial mould temperature of 200°C. The research identified the
middle and outer parts of the casting. Experimental research was preceded by numerical simulation of the casting
solidification, then a porosity assessment was carried out using the hydrostatic weighing method, which was
supplemented by structural observations. The results of the research showed a two-fold decrease in the porosity
in the middle part of the casting which is most exposed to the occurrence of shrinkage voids formed in the final
clotting phase. Structural tests revealed the occurrence of dispersed porosity in castings, mainly of shrinkage
and / or shrinkage-gas origin. The impact of pressure of 100 MPa during solidification caused fragmentation of
the primary structure of castings, which resulted in a higher grain density.