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Metals 2016, 6(5), 121;

Metallographic Index-Based Quantification of the Homogenization State in Extrudable Aluminum Alloys

Department of Mechanical Engineering, University of Thessaly, Volos 38334, Greece
Author to whom correspondence should be addressed.
Academic Editor: Nong Gao
Received: 10 April 2016 / Revised: 12 May 2016 / Accepted: 16 May 2016 / Published: 21 May 2016
(This article belongs to the Special Issue Aluminum Alloys)
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Extrudability of aluminum alloys of the 6xxx series is highly dependent on the microstructure of the homogenized billets. It is therefore very important to characterize quantitatively the state of homogenization of the as-cast billets. The quantification of the homogenization state was based on the measurement of specific microstructural indices, which describe the size and shape of the intermetallics and indicate the state of homogenization. The indices evaluated were the following: aspect ratio (AR), which is the ratio of the maximum to the minimum diameter of the particles, feret (F), which is the maximum caliper length, and circularity (C), which is a measure of how closely a particle resembles a circle in a 2D metallographic section. The method included extensive metallographic work and the measurement of a large number of particles, including a statistical analysis, in order to investigate the effect of homogenization time. Among the indices examined, the circularity index exhibited the most consistent variation with homogenization time. The lowest value of the circularity index coincided with the metallographic observation for necklace formation. Shorter homogenization times resulted in intermediate homogenization stages involving rounding of edges or particle pinching. The results indicated that the index-based quantification of the homogenization state could provide a credible method for the selection of homogenization process parameters towards enhanced extrudability. View Full-Text
Keywords: homogenization; aluminum alloys; extrudability; metallographic indices homogenization; aluminum alloys; extrudability; metallographic indices

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Sarafoglou, P.I.; Aristeidakis, J.S.; Tzini, M.-I.T.; Haidemenopoulos, G.N. Metallographic Index-Based Quantification of the Homogenization State in Extrudable Aluminum Alloys. Metals 2016, 6, 121.

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