Strain-Induced Martensitic Transformation Kinetic in Austempered Ductile Iron (ADI)

A model for the strain-induced martensitic transformation in austempered ductile iron (ADI) has been developed based on neutron diffraction studies. Quantitative phase analysis was carried out using the Rietveld method including texture analysis. The key parameters applied in this model that influence the strain-induced martensitic transformation are temperature, strain state, and loading type. An empirical relation was derived for the martensite start temperature M s in austempered ductile iron, which takes into account the Ni and carbon content. The M s temperature was used as a scaling parameter for the stability of austenite in the model to describe the strain-induced phase transformation in austempered ductile iron.