Strain Hardening Behavior of Austempered Ductile Cast Iron (ADI)

An investigation was carried out to examine the influence of austempering temperature on strain hardening behavior of austempered ductile cast iron (ADI). Cylindrical tensile specimens of nodular ductile cast iron were austempered by the conventional single-step austempering process at several temperatures. Strain hardening exponent (n values) of all these specimens were determined over the entire plastic deformation regions of the stress-strain curves. Optical microscopy and X-Ray diffraction analysis were performed to examine mechanisms of strain hardening behavior in ADI under tensile loading. Test results show that strain hardening behavior of ADI is influenced by austempering temperature and microstructural variables.