Defect formation mechanisms in lamellar graphite iron related to the casting geometry

• Although lamellar cast iron has been used in advanced applications for about 20 years, our knowledge about the mechanisms affecting microstructure and defect formation is relatively limited. The present paper summarises some solidification-related phenomena from a series of recently published peer-reviewed papers and scientific theses and suggests a mechanism of defect formation which is dependent on the shape of the solidifying casting geometry. When shrinkage porosity or metal expansion penetration occurs, evidence of material transport in the intergranular zone of primary equiaxed austenite grains in the casting and in the intergranular regions between the sand grains in the mould material is seen. Material transport occurs across the casting-mould interface, where the existence of or the permeability of the primary columnar zone determines if material transport can take place.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Metallurgi och metalliska material (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Metallurgy and Metallic Materials (hsv//eng)

Nyckelord

Columnar to equiaxed transition

Columnar zone

Defect formation mechanisms

Equiaxed zone

Lamellar graphite iron

Metal expantion penetrayion

Primary austenite grains

Shrinkage porosity

Austenite

Cast iron

Graphite

Interfaces (materials)

Iron

Molds

Porosity

Shrinkage

Textures

Defect formation

Graphite iron

Primary austenite

Defects

Mechanical Engineering

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