Design and control of chemical compositions for high-performance austempered ductile iron

This paper presents the effects of chemical compositions of austempered ductile iron (ADI) on casting quality,heat treatment process parameters and mechanical properties of final products.Through experiment and production practice,the impacts of carbon equivalent on ADI and its mechanical properties have been studied.Proper content ranges for carbon and silicon have been obtained to avoid ADI casting shrinkage and graphite floatation,as well as to achieve the optimal mechanical properties.According to the impact of silicon content on austenite phase transformation,the existing form of carbon in ADI has been analyzed,and also the formula and diagram showing the relationship between austenitizing temperature and carbon content in austenite have been deduced.The chemical composition range for high performance ADI and its control points have been recommended,to serve as a reference for production process.