A study of eutectic inoculation in grey iron by addition of Fe-Si-Ca-Al-,Sr, Ba, Zr, Ti, RE, and C.

• The interest to improve the mechanical properties and decrease shrinkage or expansion defects in grey cast irons, the inoculation is an important issue for component manufactures. The inoculation, growth of graphite and eutectic structure, are related to those demands.The paper will show a study of the effect of some inoculants on the graphite nucleation and eutectic microstructure in grey cast iron. The procedure to achieve this was to study the influence of inoculants and cooling rate on the eutectic microstructure.Six inoculants were chosen with a base of Fe-Si-Ca-Al with additions of Sr, Ba, Zr, Ti, RE and C at different proportions. Two of the inoculants were investigated at three different levels of additions. The inoculants gave eutectics with great variety of microstructure. The experimental equipment was designed to produce cast samples under controlled thermal conditions and equipped with thermocouples. To study the influence of cooling rate on the eutectic nucleation, the mould was equipped with three different cooling conditions. In order to measure the eutectic cell size the samples were colour etched. The measurements were made near the thermocouples to relate the eutectic cell size and cells/area with the cooling curves. The microstructure, cell-size and cooling curves were used to model the nucleation behaviour of the investigated compositions and solidification behaviour. The investigation showed that the type and amount of inoculation influenced the number of potent nuclei of graphite eutectic and the fading followed Lifshitz-Slyosov-Wagner (LSW) theory of ripening.

Ämnesord

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

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

Nyckelord

Grey east iron

solidification

graphite eutectic nucleation

inoculants

fading

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