Predicting the Hounsfield Unit (HU) of Aluminum Alloy AA2011 From the Weight Fractions of its Alloying Elements: An X-Ray Computed Tomography Study

Abstract

X-ray computed tomography scans are being increasingly employed as a non-destructive testing method for the detection of internal defects and material identification. However, mean Hounsfield Unit (HU) measurements for many metals and alloys are unreported in the literature due to the high HU values of metals and their alloys and also due to the wide range of possible combinations of X-ray scanning parameters. For this reason, developing a method that can accurately predict the mean Hounsfield unit value of a material given its elemental composition and mean Hounsfield measurements of its constituent elements is valuable and can help fill the gap for under-reported materials. In this study, first, the mean Hounsfield values for AA2011 are predicted using two methods based on the mixture model. Second, the effect of the X-ray scanning parameters on the predictive accuracy of the mean Hounsfield Unit value for AA2011 is studied. To this end, X-ray CT scans are performed at three X-ray tube current levels (50, 100, and 200 mAs) and two tube voltage levels (120 and 140kVp). Also considered is the effect of scan window size (field of scan view) as represented by voxel size where three sizes (0.00287, 0.0176, and 0.0452 mm3) are utilized. The effect of sample thickness is assessed via three thickness levels (1.5, 3, and 6 mm). The findings show that both methods show good predictive ability with the second method showing greater accuracy.