ESTUDO SOBRE A NUCLEAÇÃO E CRESCIMENTO DE NÓDULOS DE GRAFITA EM FERROS FUNDIDOS NODULARES
STUDY ON NUCLEATION AND GROWTH OF NODULAR GRAPHITE PARTICLES IN DUCTILE CAST IRON
André de Albuquerque Vicente, Victor Bridi Telles, Amilton Barbosa Botelho Junior, Susana Marraccini Giampietri Lebrão, Denise Crocce Romano Espinosa, Jorge Alberto Soares Tenório
Resumo
Foram estudadas três corridas comerciais de ferro fundido nodular. Para produção das corridas, partiu-se do mesmo metal base e utilizou-se a mesma liga nodularizante. Cada uma das corridas foi feita com inoculantes diferentes. Os percentuais em peso de inoculante e liga nodularizante foram, respectivamente, 1,0% e 1,3%. Estudou-se a nucleação e o crescimento dos nódulos de grafita. Várias técnicas complementares de análise microestrutural foram utilizadas, tais como microscopia óptica, microscopia eletrônica de varredura (MEV) e espectroscopia de raios-X por dispersão de energia (EDS). Observou-se a sequência de crescimento dos nódulos de grafita, evidenciando-se a formação de silicatos complexos ricos em alumínio, cálcio e bário ao redor dos núcleos, gerando uma interface favorável à solidificação heterogênea de grafita a partir destas partículas de tamanho superior ao raio crítico.
Palavras-chave
Abstract
Three commercial ductile cast iron heats were studied. The same base metal and nodularization alloy were used. Each of the heats was made with different inoculants. The weight percentage of inoculant and nodularization alloy were respectively 1.0% and 1.3%. The nucleation and growth of the nodular graphite particles were studied. Several complementary techniques for microstructural analysis were used, such as optical microscopy, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). It was observed the growth sequence of spheroid nodular graphite particles, demonstrating the formation of complex silicates rich in aluminium, calcium and barium around the core, creating a supportive interface to the heterogeneous solidification of graphite from these particles larger than the critical radius
Keywords
Referências
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