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Microstructural characterization of the AA7004 and AA7075 thixoforging alloys in an eccentric press

ABSTRACT

The aim of this work was to analyze the thixoforging process in an eccentric press of the AA7004 and AA7075 aeronautical alloys and to understand the behavior of the semisolid material during the filling of the die through microstructural analysis. The alloys were subjected to globularization heat treatments for 210 seconds and liquid fraction of 55% and in the sequence thixoforged. Working temperatures were determined via DSC tests (differential scanning calorimetry). The globularization heat treatments aim to effect the partial or total globularization of the alloys, allowing the analysis of microstructural evolution. The maximum force applied in the thixoforging process was approximately 500 kg, and the capacity of the eccentric press according to its manufacturer is 25 tons, demonstrating that the force used to perform the tests was negligible compared of the capacity of the equipment. The thixoforged final product presented total filling of the die and dimensional quality. The part in the center of the final product, where the biggest deformation occurred, presented deformed and smaller grains in relation to the other parts, namely the AA7004 alloy presented a grain size of 142 µm and the AA7075 alloy presented a grain size of 105 µm.

Keywords
Thixoforging; semi-solid material; eccentric press; AA7004; AA7075

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