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Doctoral Thesis
DOI
https://doi.org/10.11606/T.3.2021.tde-07102021-145604
Document
Author
Full name
Saul Hissaci de Souza
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2021
Supervisor
Committee
Padilha, Angelo Fernando (President)
Couto, Antonio Augusto
Kliauga, Andrea Madeira
Lima, Nelson Batista de
Plaut, Ronald Lesley
Title in Portuguese
Estudo do encruamento, recristalização e evolução da textura cristalográfica da liga de alumínio AA 7108.
Keywords in Portuguese
Envelhecimento natural
Ligas de alumínio
Textura cristalizada
Abstract in Portuguese
O presente trabalho apresenta um estudo acerca da evolução da textura cristalográfica durante o processamento da liga de alumínio AA 7108. As amostras foram recebidas na forma de barras extrudadas a quente e caracterizadas com as técnicas de microscopia óptica de luz polarizada, microscopia eletrônica de varredura, condutividade elétrica e ensaios de microdureza Vickers. A textura cristalográfica das amostras extrudadas foi estudada via difração de elétrons retroespalhados (microtextura) e difração de raios - X (macrotextura). Observou-se que existia variação de textura cristalográfica ao longo da espessura da barra extrudada: enquanto uma textura de componente Cubo <100> foi encontrada na superfície de extrusão, uma componente adicional do tipo Goss <100> foi encontrada na região correspondente ao centro da barra. Após caracterização inicial, as amostras foram solubilizadas a 490°C por 5 horas e, em seguida, estudou-se a variação de dureza e de condutividade elétrica dessas amostras com o passar do tempo. Observou-se (por meio do aumento da dureza) a elevada capacidade de envelhecimento natural do material. Percebeu-se também que, ao contrário do poderia se esperar, as amostras solubilizadas possuíam condutividade maior do que as amostras naturalmente envelhecidas. A seguir, as amostras solubilizadas foram laminadas a frio utilizando-se duas reduções de espessura (33,7% e 63,6 %), sendo que cada redução foi obtida variando-se o número de passes. As amostras laminadas com maior número de passes mostraram tendência à formação de uma componente de textura Goss <100>, enquanto as amostras laminadas com um menor número de passes apresentaram maior dispersão de componentes de textura, tendendo, além da componente Goss, formar a componente do tipo Latão <211>. Após recozimento a 490°C, observou-se que as amostras deformadas com maior velocidade apresentaram microestrutura parcialmente recristalizada e textura com intensa componente (113) <332>, enquanto as amostras deformadas com menor velocidade apresentaram intensa recuperação e mantiveram a textura próxima à Goss <100> além de outras componentes ao longo da fibra <110>.
Title in English
Evaluation of strain hardening, recrystallization and crystallographic texture for an AA 7108 aluminum alloy.
Keywords in English
AA 7108
Aluminum alloys
Crystallographic texture
Natural aging
Abstract in English
The present work presents a study about the evolution of crystallographic texture of aluminum alloy AA 7108 strips after thermomechanical process. The samples were received as hot extruded bars and characterized by optical microscopy of polarized light, scanning electron microscopy, electrical conductivity and Vickers hardness tests. The crystallographic texture as received samples was studied by electron backscatter diffraction (microtexture) and X - ray diffraction (macrotexture). It was observed that there was change of crystallographic texture along the thickness of the extruded bar: While a Cube component texture (<001> <100>) was found on the extrusion surface, an additional Goss component ( <100 >) was found at half thickness of the bar. After initial characterization, the samples were solubilized at 490°C for 5 hours and then the hardness and electrical conductivity variation of these samples were studied over time. The high natural aging capacity of the material was observed (by the hardness increasing) and it was found that, unlike one could expect, the solubilized samples had higher conductivity than the natural aged samples. The solubilized samples were then cold rolled by using two thickness reductions (33.7% and 63.6%), each reduction was obtained by varying the number of passes. The deformed strips were studied by using the same techniques described above. The rolled samples strained by using a larger number of passes showed a tendency to form a well-defined texture component (Goss <100>), while the rolled samples strained by using a lower number of passes had a greater dispersion of texture components, tending, in addition to the Goss component, to form the Brass component ( <211>). After an annealing at 490°C, it was observed that the samples rolled with higher strain rate presented a partially recrystallized microstructure and texture with intense (113) <332> component, whilst samples rolled with lower strain rate presented intense recovered microstructure and kept Goss <100> texture component.
 
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Publishing Date
2021-10-18
 
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