Thermo-magnetic processing of ductile cast iron

In this investigation, austempered ductile cast iron (ADI) with a fully ferritic microstructure was produced by a novel thermo magnetic austempering process. This novel process consists of austempering of ductile cast iron in a high magnetic field of 20 T. Unalloyed ductile cast iron samples were initially austenitized at 927 °C (1700 °F) for 2 h and then quenched in a salt bath to an austempering temperature of 260 °C (500 °F). The samples were austempered at this temperature for 0.5 h in the presence of a strong external magnetic field of 20 T around the salt bath chamber and test samples. This resulted in a fully ferritic microstructure. The microstructure and mechanical properties of the resulting material have been characterized and compared with conventionally processed austempered ductile cast iron at the same temperature (260 °C) without magnetic field.