Abstract
A computer model has been developed to predict the processing window (austempering window) for austempered ductile iron (ADI). The model is a modification of an existing model for the isothermal decomposition of austenite in bainitic steels. It was calibrated using experimental data from the literature. In order to validate the model, the processing window corresponding to a ductile iron of composition 3.41%C, 2.46%Si, 0.36%Mn, 0.18%Mo, and 0.25%Cu is predicted and compared to experimental data. Computer assisted image analysis was used to investigate the volume fraction of martensite at the lower boundary of the processing window. X-ray diffraction was used to calculate the normalised volume fraction of austenite at the upper boundary of the processing window. The results show that the model successfully predicts the processing window corresponding to the iron investigated in this study.
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