Artigos Científicos - ITEC
URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/3360
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Item Acesso aberto (Open Access) Effect of the T6 Heat Treatment on Microhardness of a Directionally Solidified Aluminum-Based 319 Alloy(Universidade Federal do Pará, 2017-11) MAGNO, Igor Alexsander Barbosa; SOUZA, Fabricio Vinicius Andrade de; BARROS, André dos Santos; COSTA, Marlo Oliveira; NASCIMENTO, Jacson Malcher; COSTA, Thiago Antônio Paixão de Sousa; ROCHA, Otávio Fernandes Lima daAluminum alloys of the ANSI series 319 present Si and Cu as the main alloying elements and the mechanical strength of these alloys can be improved by the precipitation of the metastable Al2Cu phase during the ageing heat treatment. In this paper, the Al-5.5wt.%Si-3wt.%Cu alloy was elaborated and solidified in a water-cooled horizontal directional solidification device. The as-cast ingot was subjected to the precipitation hardening heat treatment (T6 heat treatment), which consisted of: solution for 5 h at 490°C±2°C, followed by quenching in water at 60°C±2°C and ageing for 3 h at 155°C±2°C, and cooling-air. Secondary dendrite arm spacing (λ2) measurements were carried out before and after T6 heat treatment. The mechanical strength of the alloy was investigated by the microhardness test. It has been found that the heat treatment did not influence the λ2 values, however, highest HV values have been observed for the heat-treated samples.Item Acesso aberto (Open Access) Fracture modes of AISI type 302 stainless steel under metastable plastic deformation(Associação Brasileira de Metalurgia e Materiais, 2017-11) SANTOS, Jheison Lopes dos; MONTEIRO, Sergio Neves; CÂNDIDO, Veronica Scarpini; SILVA, Anderson Oliveira da; RAMOS, Flávio James Humberto Tommasini VieiraMartensitic transformation can be induced by plastic deformation in metastable iron-based alloys, such as stainless steels containing limited amounts of C, Ni and Cr. This transformation takes place at the temperature range from Ms and Md, usually at relatively lower temperature values. The transformed martensite has been associated with maximum ultimate strength and relatively high ductility. In the present work, the tensile fracture characteristics of a metastable AISI type 302 stainless steel was properties were compared to those of a stable AISI type 310 austenitic stainless steel. It was found that in 302 steel, its high degree of metastability and dilute dispersion of inclusions result in higher strength and complex modes of fracture, one of which consisting of martensite surrounding globular inclusions.