Solidification of steels involving the peritectic reaction are inherently prone to longitudinal facial cracking during casting, owing primarily to the large volume shrinkage associated with delta-ferrite to austenite transformation occurring at high temperatures. Therefore casting of those steels requires a lot of caution. Ferrite Potential (FP) is widely accepted as a measure of the tendency of steels to form delta-ferrite during solidification. However, the most commonly used definition of Ferrite Potential is strictly applicable only to plain carbon steels while commercial steels may contain several other alloying elements. Therefore, the existing definition may not express their actual Ferrite Potential. In view of this, a new correlation has been developed in the present work for evaluating the true Ferrite Potential for multi-component steels. Influences of several common alloying/solute elements have been considered while developing the present model. Present model development involved rigorous thermodynamic calculations aimed at determining the interactions among various solute elements and their overall influence on the peritectic compositions and the peritectic transformation temperature. In addition, assumed quadratic dependence of peritectic compositions and temperature on the concentrations of alloying elements has been employed besides the application of non-linear multi-variate regression analysis. Finally, present correlations have been extensively validated against literature data as well as actual plant observations. In comparison to other models, reasonably better agreement between the current model predictions and plant data has been obtained. The present model has helped the plant operators in selecting the right parameters for casting operations.
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