Properties of ductile cast iron nodularised with multiple calcium-magnesium based master alloy

Austempered ductile iron (ADI) is gradually replacing many fabricated and forged steel components in engineering applications; One of its advantages is the combination of good castability, machinability, and mechanical properties with significant savings in cost and weight compared with equivalent steel components. A problem in the production of ADI is the use of expensive and dangerously reactive magnesium as a graphite nodulariser. There is a need to find cheaper, safer, and equally effective substitutes. Results of an investigation of the effectiveness of a multiple calcium-magnesium based master alloy nodulariser and the properties of the ductile iron and ADI produced are reported. Up to 96% nodularity could be obtained using a special Ca-CaC2-Mg master alloy, compared with 98% using magnesium alone. The mechanical properties were also comparable. MST/4187.