Submitted by AMELIA ALIK DE FREITAS ZUMBA null (amelia.zumba@novelis.com) on 2016-09-28T20:39:28Z No. of bitstreams: 1 Mestrado - v.final.docx: 10697220 bytes, checksum: 300f19fc7542fa3470679a32d14fa78c (MD5) / Rejected by Ana Paula Grisoto (grisotoana@reitoria.unesp.br), reason: Solicitamos que realize uma nova submissão seguindo as orientações abaixo: A versão final da dissertação/tese deve ser submetida no formato PDF (Portable Document Format). O arquivo PDF não deve estar protegido e a dissertação/tese deve estar em um único arquivo, inclusive os apêndices e anexos, se houver. Por favor, corrija o formato do arquivo e realize uma nova submissão. Agradecemos a compreensão. on 2016-09-29T18:34:10Z (GMT) / Submitted by AMELIA ALIK DE FREITAS ZUMBA null (amelia.zumba@novelis.com) on 2016-09-29T20:05:22Z No. of bitstreams: 1 Mestrado - v.final.pdf: 2498608 bytes, checksum: df0eee2f47b660e50ddb61b07e057fb8 (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-09-30T16:44:59Z (GMT) No. of bitstreams: 1 zumba_aaf_me_guara.pdf: 2498608 bytes, checksum: df0eee2f47b660e50ddb61b07e057fb8 (MD5) / Made available in DSpace on 2016-09-30T16:44:59Z (GMT). No. of bitstreams: 1 zumba_aaf_me_guara.pdf: 2498608 bytes, checksum: df0eee2f47b660e50ddb61b07e057fb8 (MD5) Previous issue date: 2016-08-02 / Há uma crescente demanda pelo uso de materiais na indústria em geral, que consigam aliar sustentabilidade e performance, onde o alumínio enquadra-se nestes dois requisitos. A liga AA5182 apresenta propriedades importantes, tais como: baixa densidade, alta resistência mecânica e à corrosão, bem como boa conformabilidade. Neste estudo, foi realizada a definição de uma região crítica na qual foram realizados três testes, simulando diferentes ciclos de homogeneização desta liga, através da realização do ciclo de homogeneização em menores tempos que o ciclo original, antes do envio para a laminação a quente e avaliando características superficiais e microscópicas, para que não exista impacto negativo nos processos subsequentes. Após as análises comparativas realizadas, percebeu-se que o teste onde o patamar de aquecimento foi abaixo da temperatura de liquação de precipitados de magnésio apresentou melhor resultado, proporcionando a redução do tempo de ciclo sem o aparecimento de linhas pretas, oriundas da oxidação do magnésio, permitindo assim, a redução do tempo de ciclo de homogeneização. / There is a growing demand for the use of materials in the industry in general, they can combine sustainability and performance, where aluminum fits these two requirements. The alloy AA5182 has important properties such as: low density, high mechanical resistance and corrosion resistance as well as good formability. First of all, this study was conducted to define a critical region in which there were three tests, simulating different homogenization cycles of this alloy, by conducting the homogenization cycle times smaller than the original cycle, prior to shipment to the hot rolling and evaluating superficial and microscopic characteristics, so that there is no negative impact on subsequent processes. After that, comparative analyzes it was observed that the test where the heating level was below the magnesium precipitates liquation temperature showed better results, providing a reduction in the cycle time without the appearance of black streaks, derived from the magnesium oxidation, thus, reducing the homogenization cycle time.

Static abnormal grain growth (SAGG) was studied in Al-Mg alloy AA5182 sheet by varying four processing parameters: deformation temperature, strain rate, annealing temperature, and annealing time. SAGG is a secondary recrystallization process related to geometric dynamic recrystallization (GDRX) and requires both deformation at elevated temperature and subsequent static annealing. A minimum temperature is required for both SAGG and GDRX. Recrystallized grains only develop at strains larger than the critical strain for SAGG, [epsilon]SAGG. The size of the recrystallized grains is inversely related to and controlled by the density of SAGG nuclei, which increases as local strain increases. The results of this study suggest that SAGG is controlled by two thermally-activated mechanisms, dynamic recovery and recrystallization. During deformation, dynamic recovery increases as deformation temperature increases or strain rate decreases, increasing the critical strain for SAGG. SAGG is subject to an incubation time that decreases as annealing temperature increases. SAGG can produce grains large enough to reduce yield strength by 20 to 50 percent. The results of this study suggest strategies for avoiding SAGG during hot-metal forming operations by varying processing conditions to increase [epsilon]SAGG. / text

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