Supporting the model of ductile iron dendritic solidification

• Autor(a) principal: Santos, Henrique
• Data de Publicação: 2000
• Outros Autores: Pinto, A. M. P., Jacinto, Maria, Sá, Carlos
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/1822/1786
• topic: Ductile Iron; Solidification; Science & Technology

The literature about graphite formation in ductile iron proposes the experimentally supported theory lhat this phase forms in the melt. This is naturally accepted as a consequence af the euteclic reaction of the iron-carbon equib"briumdiagram. This reaction requires that during cooling, at 1150-1100°C, the liquid with a eutectic composition decomposes into two solid phases, pure graphite aOOaustenite with a earbon content dose to 2% in weight. li the ductile irons have a generaIly eutectic composition, the presence of neither pro-eutectic graphite nor austenite seems necessary for eutectic graphite formation. According to the proposed solidification path, the graphite nodules become encapsulated by an austenite case, resulting in a 10ss of conmct between liquid and graphite. Carbon will then have to diffuse from the liquid through the austenite to the graphite to allow further growth 01both solid phases.