Porosity Characterization of Aluminium Castings by Using Particular Non-destructive Techniques

Abstract

In this paper is presented an analysis of a comparison of particular non-destructive techniques: radiographic, ultrasonic, eddy current and pulsed infrared thermography to detect flaws in pressure die casting. Furthermore, a new way of the image segmentation method for porosity detection in aluminium pressure die casting using results from X-ray analysis and public domain software is proposed. The results of the research allowed verifying the possibility of using the aforesaid methods in controlled technological parameters of the casting process, and thus permitted confirming the quality of the manufactured castings. It was found that the radiographic method was the most preferred means for evaluating the quality of products and for optimizing the technological process for aluminium pressure casting. It permits a fast analysis of casting defects in the finished products, and when combined with the computer image analysis (the porosity segmentation algorithm as described in the article) it allows drawing conclusions regarding their causes (e.g. based on the size and shape analysis of the pores detected). The ultrasonic testing method can also be used to evaluate the quality of the casting (to detect it but without the possibility of interpreting the size or source of origin). The results obtained via this method allow for proper control of die casting parameters.