Mechanism of silicon influence on the chill of cast iron
نویسنده
چکیده
In this work an analytical solution of general validity is used to explain mechanism of the silicon influence on the absolute chill tendency (CT) and chill (w) of cast iron. It is found that CT can be related to nucleation potential of graphite (Nv), growth parameter (μ) of eutectic cells, temperature range (∆Tsc) and the pre-eutectic austenite volume fraction (fγ). It has been shown that silicon additions: a) impede the growth of graphite eutectic cells, μ, b) expands the temperature range ∆Tsc, c) increases the nucleation potential of graphite Nv, d) lowers the pre-eutectic austenite volume fraction, fγ. and in consequence the absolute chilling tendency, CT decreases. The minimum wall thicknesses for chilled castings, or chill widths (w) in wedge shaped castings is related to CT and as silcon contents increases, the w value also increases.
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