Abstract
The processing window enables the heat treater to produce an austempered ductile iron that satisfies the ASTM standard A897M:1990. The aim of the present study is to determine whether a bainite transformation model developed for steels is applicable for calculating the extent of the processing window for an austempered ductile iron ADI of composition wt- Fe-3.55C-2.72Si-0.25Mn-0.25Mo-0.25Cu-0.04Mg. The bainitic model is calibrated for the start of the processing window, according to an autocatalysis factor that describes the extent to which the formation of one plate of ferrite activates others. The time interval between the beginning and the end of the processing window is used for estimation of the end of the processing window. Experimental data sourced from the literature for the ADI are used to calibrate the model, and it is shown that the bainitic model is applicable for calculation of the processing window. Further upgrading of the model is required for its application to ADIS of various compositions.
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