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ArticleName PoDFA-based computer-aided analysis of non-metallic inclusions in aluminium alloys using image analysis
DOI 10.17580/tsm.2019.03.06
ArticleAuthor Kazakov А. А., Kiselev D. V., Kur А. А.

1Thixomet Ltd., Saint Petersburg, Russia ; 2Peter the Great St. Petersburg Polytechnic University, Saint Petersburg, Russia:

А. А. Kazakov, CEO1, Head of Metallurgical Examination Laboratory2, e-mail:
D. V. Kiselev, Technical Director1, Engineer at Metallurgical Examination Laboratory2
А. А. Kur, Engineer1, Associate Professor at the Department of Metallurgical and Casting Technologies2


The algorithm for the automated determination of the contamination of aluminum alloys by non-metallic inclusions using the PoDFA technique has been developed and implemented as a software module for the Thixomet Pro image analyzer. The adaptive algorithm of image segmentation provides automatic recognition of clusters of inclusions in the background of a metallic matrix with uneven illumination, including areas with metal relief, both from the metal side at the metal-filter interface and in the filter pores filled with metal to a depth of 0.5 mm. Clusters of inclusions of different types are separated automatically according to their optical and morphological characteristics. A high-performance clustering algorithm based on Euclidean distance mapping allows a real-time distribution of inclusions even with full-size panoramic images of the entire surface of the cross section, taking into account the combination of inclusions according to the “5 μm” and “20 μm” rules of the PoDFA method. The accuracy, reproducibility and performance of an assessment have been improved, as well as the subjectivity of the analysis of samples by the PoDFA technique has been reduced compared to the previously used visual assessment by manual methods. The developed module has been successfully tested in industrial laboratories at specialized enterprises. Examples of the image analyzer applying for the analysis and interpretations of the inclusion’s nature for the commercial PoDFA samples selected inside the filter in a АА 3104 alloy, in a continuous layer of inclusions in АА 6063 alloy before a filtration; and, in conditions of complex multicomponent conglomerates of inclusions in aluminum of technical cleanliness, have been discussed. Significant shortcomings of the PoDFA methodology limiting its accuracy, reproducibility and performance have been identified which motivate the development of a more advanced national technique for assessing the contamination of aluminum alloys by nonmetallic inclusions.

keywords Aluminum alloys, nonmetallic inclusions, PoDFA, automated evaluation, image analysis, quality control, quantitative analysis, metallographic

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