Investigation of texture development and Portevin-Le Chatelier bands in 5754 aluminum alloy

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2019
Aytuna, Orhan Berk
Texture and microstructure are substantial parameters for final products which are made of non-heat treatable aluminum alloys such as 5xxx series. Optimizing these parameters is possible via deformation processes and following heat treatments. In this thesis; hot and cold rolling operation, as a basic deformation process, was applied to the aluminum and resulting copper, brass and cube type of texture was investigated. Effects of different annealing parameters on the deformed specimens were also analyzed with texture development and microstructural features such as recrystallization and abnormal grain growth. It was also detected that mechanical behavior of this alloy was also affected by nucleation and propagation of Portevin-Le Chatelier bands under various strain paths. Therefore, an in-plane biaxial test apparatus was utilized with a miniature cruciform specimen to achieve uniaxial and equibiaxial strain paths. The magnitude of load serrations and inhomogeneous strain distributions due to PLC effect were examined with load cells and digital image correlation technique, respectively. Under biaxial stretching, PLC bands nucleated and propagated repeatedly at the same region of the specimen, while their formation was random under uniaxial tension. Due to shear stresses in uniaxial tension, PLC bands were promoted and evolved into sharp visible shear bands which cause eventual failure of product. Texture analysis also confirmed the emergence of shear components and cube texture with increasing strain. Conversely, biaxial deformation conditions were beneficial for prevention of undesired fracture from shear bands even if PLC strain contribution to the total strain was higher than uniaxial conditions.

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Citation Formats
O. B. Aytuna, “Investigation of texture development and Portevin-Le Chatelier bands in 5754 aluminum alloy,” Thesis (M.S.) -- Graduate School of Natural and Applied Sciences. Metallurgical and Materials Engineering., Middle East Technical University, 2019.