Characterisation of defects in die cast aluminium parts

Abstract

In this paper, the results of computed tomography and destructive testing of a die cast, gas tight aluminium part are compared and analysed with the aim of refining the porosity map. The mapping of the continuity defects detected by the two methods makes it possible to estimate the number, shape and distribution of continuity defects on and in the immediate vicinity of the machined surface, and to compare the characteristics of continuity defects detected by non-destructive and sequential fine machining. Based on the results of the CT scan of a given casting, we also performed destructive testing to find defects in a selected part of the casting by sequential fine machining. The basic criterion for the choice of the cutting parameters was to minimize the plastic deformation (smearing) on the machined surface, i.e. to clearly identify porosity. We then investigated the position, shape and other characteristics of porosity on the surfaces. The results and differences resulting from the two different methods are also analysed.