Efeito da Taxa de Resfriamento e dos Tratamentos Térmicos sobre as Propriedades Mecânicas da Liga Al-Si-Mg (A356.0) Fundida / Efeito da Taxa de Resfriamento e dos Tratamentos Térmicos sobre as Propriedades Mecânicas da Liga Al-Si-Mg (A356.0) Fundida

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

15/12/2011

RESUMO

The A356.0 alloy is widely used in aerospace and automotive industry and other structural applications which require high mechanical strength. The control of solidification cooling rate and heat treatments are necessary to obtain more appropriate microstructures resulting in improvement of their properties. In this paper was evaluated the influence of cooling rate imposed by the different mold materials and heat treatment (T6) on the microstructures formed in samples of the alloy A356.0. In addition the influence of these microstructural changes on mechanical properties of alloy was evaluated. The samples were cast in sand mold, in metal mold without and with cooling cooled and then heat treated. The structure refinement was greater in the metallic mold cast than the sand cast sample, due to the higher cooling rate. The heat treated samples showed that the morphology of the Al-matrix has not changed. The silicon particles undergo fewer fragmentations and spheroidization in the sand cast samples compared to the samples cast in metallic molds. The mechanical properties were measured by means of tensile test, Charpy impact and Brinell hardness. The ingots produced in the sand mold present a coarse microstructure, which is a determining factor for the decrease in mechanical properties of the alloy. In some ingots produced in the cooled metal mold the presence of micropores was observed probably, being responsible for the decrease in mechanical properties. The ingots produced in the metal mold (without cooling and cooled), where the heat extraction rate was higher, showed finer microstructure with smaller dendritic spacing. Such a microstructure provided the best mechanical characteristics of the samples. The T6 heat treatment significantly improved the mechanical properties of the alloy. The precipitation of the metastable supersaturated solution Mg2Si was the main factor promoting the increase of mechanical strength.

ASSUNTO(S)

liga a356.0 espaçamentos dendríticos tratamento térmico t6 mg2si metaestável a356.0 alloy dendritic spacings t6 heat treatment metastable mg2si engenharia de materiais e metalurgica

ACESSO AO ARTIGO

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