Efeito da espessura do fundido (de 3,2 a 5,8 mm) no limite de resistência de ferro fundido cinzento perlítico
Effect of the casting thickness (3.2 to 5.8 mm) on the tensile strength of grey cast iron
Felipe Fonseca de Oliveira Lima, Cesar Roberto de Farias Azevedo
Resumo
O limite de resistência e a macro e microestruturas de ferro fundido cinzento perlítico com carbono equivalente igual a 4,25% foram investigados para espessuras de parede variando entre 3,2 e 5,8 mm (velocidade de resfriamento entre 29 e 6°C/s). Foram empregadas técnicas de caracterização microscópica para quantificar os principais parâmetros macro e microestruturais. A redução da espessura do fundido promoveu o refino do espaçamento secundário dos braços de dendritas de austenita (SDAS), do tamanho médio das células eutéticas (TMCE), do tamanho médio das colônias de perlita (TMCP), do espaçamento interlamelar médio da perlita (λperlita) e do diâmetro hidráulico interdendrítico (DHid). Como consequência, ocorreu um aumento no valor máximo do limite de resistência à tração de 274 para 420 MPa com o aumento da velocidade de resfriamento. Esses resultados foram usados para testar dois modelos matemáticos de predição do limite de resistência de ferros fundidos cinzentos perlíticos em função de seus parâmetros macro e microestruturais.
Palavras-chave
Abstract
The tensile strength and the macro and microstructures of pearlitic grey cast iron with wall thickness varying from 3.2 to 5.8 mm (cooling velocity between 29 e 6°C/s) were investigated. Microscopic characterization techniques were employed to quantify the main macro and microstructural parameters. The reduction in cast thickness refined the austenite dendrite arm spacing (SDAS), the mean size of the eutectic cell (TMCE), the mean size of the pearlite colonies (TMCP), the pearlitic interlamellar spacing (λpearlita) and the interdendritic hydraulic diameter (DHid). Consequently, there was an increase in the average value of the tensile strength from 274 to 420 MPa due to the increase of the cooling velocity. These results were used to test two mathematical models, which use the macro and microstructural parameters of the pearlitic grey cast irons to predict their tensile strength.
Keywords
Referências
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Submetido em:
01/04/2020
Aceito em:
20/07/2020
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