Quality mapping of aluminium alloy diecastings

The effect of casting defects on mechanical properties was investigated for a high-pressure die-cast aluminium alloy. A series of U-shaped components were cast using a fully controlled cold chamber high-pressure die-casting machine with different process parameters. Defects existed in gas and shrinkage pores as well as oxide inclusions. An X-ray equipment was used for a preliminary quality control but showed its limits in detecting defects. The castings were sectioned and tensile bars extracted from different locations in the castings in order to map the distribution of the mechanical properties. The decrease in mechanical properties correlated with the area fractions of defects revealed on the fracture surface of the tensile specimens. A quality mapping approach showed how the final properties depend on the position of the casting and the process parameters adopted.