Abstract

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The quantity of carbon-enriched stabilised austenite (γHC) in austempered ductile iron (ADI) with various casting thicknesses was evaluated in this study. Ductile iron grade that conforms to ASTM A536 65-45-12 was cast, specimens of section thickness in the range of 5 to 25 mm were machined, isothermally treated to 820°C austenitising temperature, and austempered at austempering temperature (T ) of 300 and 375°C. The resulting phase distributions A of treated specimens were characterised using X-Ray Diffraction (XRD) method. The patterns of XRD were found to consist of ferrite (α) and austenite (γ) phases. The percentage volume of carbon-enriched stabilised austenite in the ADI decreased as section thickness increased. It was concluded that the carbon-enriched stabilised austenite in ADI depends on the casting section thickness and austempering temperature

Keywords: Ductile iron; Aaustempered ductile iron; Carbon stabilised austenite; Acicular ferrite; Casting thickness