Navegando por Assunto "Fracture"

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Acesso aberto (Open Access)
Caracterização mecânica e metalúrgica de parafusos da classe 10.9, utilizados na fixação da suspensão dianteira de veículos CAT793D, aplicando tratamento termoquímico de cementação
(Universidade Federal do Pará, 2022-08-31) RABELO JÚNIOR, Fábio Alves; CARDOSO FILHO, José Carlos de Araújo; QUARESMA, José Maria do Vale; http://lattes.cnpq.br/7443111804471290
When a structural component of a large piece of equipment fails, catastrophic consequences can occur, generating highly measurable economic losses, because a failure leads to an interruption of an entire production line and damage to the workflow, which can cause delays and increased maintenance costs, whether preventive or corrective. In addition, serious risk conditions affect the loss of life in cases of catastrophic accidents, where they are widely reported by the media and strongly influence an organization's conduct. The objective of this work is to carry out the mechanical and metallurgical characterization of screws of class 10.9, applying the Thermochemical Treatment of Cementation, evaluating the influence of this mechanical resistance. These components include the Caterpillar model 793D “Off-Highway” truck suspension system that carries heavy iron ore loads in the Ferro-Carajás complex, in the state of Pará. Thermo-chemical treatments and mechanical tests were carried out and Tensile Stress. Fractographic and Microstructural analyzes were performed using Scanning Electron Microscopy - SEM, in addition to Optical Microscopy.
Acesso aberto (Open Access)
Correlação da coalescência de microcavidades com as propriedades mecânicas e elétricas de fios para Tx e Dx de energia elétrica da liga base Al-0,5%Cu-[0,24-0,28]%Fe modificada com teores de silício
(Universidade Federal do Pará, 2013-07) MONTEIRO, Valmor Capanema Oliveira; QUARESMA, José Maria do Vale; http://lattes.cnpq.br/7443111804471290
In this study, na attempt is made to establish the influence of the concentration [0.5, 0.7 and 0.9]% Si as modifiers of alloys Al-0,05% Cu-[0.24 to 0.28]%Fe, evaluated by aspects that took into account operational parameters such as horizontal unidirectional leaks: Speeds (Vs) and Exchange Solidification (Tx). After cutting and machining cylindrical profiles were obtained with diameters of 9.5mm and length of 120mm, from which, after the cold working operations, were obtained wires with diameters of 2.7, 3.0, 3.8 and 4.0 mm. These profiles were subjected to electrical characterization on the basis of the electrical conductivity, tomechanical characterization based on assays stress/strain, emphasizing elongation [%], and structural characterization longitudinal sections, with emphasis on distribution of second phase particles, and aspect of the fracture, with emphasis on the relationship L/W length (L) and width (W) of the dimples.