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Tham khảo tài liệu 'casting (1998) part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | MALLEABLE IRON is a cast ferrous metal that is initially produced as white cast iron and is then heat treated to convert the carbon-containing phase from iron carbide to a nodular form of graphite called temper carbon. There are two types of ferritic malleable iron blackheart and whiteheart. Only the blackheart type is produced in the United States. This material has a matrix of ferrite with interspersed nodules of temper carbon. Cupola malleable iron is a blackheart malleable iron that is produced by cupola melting and is used for pipe fittings and similar thin-section castings. Because of its low strength and ductility cupola malleable iron is usually not specified for structural applications. Pearlitic malleable iron is designed to have combined carbon in the matrix resulting in higher strength and hardness than ferritic malleable iron. Martensitic malleable iron is produced by quenching and tempering pearlitic malleable iron. Malleable iron like ductile iron possesses considerable ductility and toughness because of its combination of nodular graphite and low-carbon metallic matrix. Because of the way in which graphite is formed in malleable iron however the nodules are not truly spherical as they are in ductile iron but are irregularly shaped aggregates. Malleable iron and ductile iron are used for some of the same applications in which ductility and toughness are important. In many cases the choice between malleable and ductile iron is based on economy or availability rather than on properties. In certain applications however malleable iron has a distinct advantage. It is preferred for thin-section castings for parts that are to be pierced coined or cold formed for parts requiring maximum machinability for parts that must retain good impact resistance at low temperatures and for some parts requiring wear resistance martensitic malleable iron only . Ductile iron has a clear advantage where low solidification shrinkage is needed to avoid hot tears or where the .