A THEORETICAL-ANALYSIS OF THE CHILLING SUSCEPTIBILITY OF HYPOEUTECTICFE-C ALLOYS

In this work an analytical solution of general validity is proposed to explain the chill tendency of cast iron of different compositions. A balance of the various heat contributions during the solidification pr ocess is employed in arriving at an expression for the chilling equiva lent E. It is found that E can be directly related to the modulus of t he casting and it includes the effects of (a) nucleation and growth of pro-eutectic as well as eutectic phases, (b) the range of metastabili ty, and (c) the pouring temperatures. Moreover, the predictions of the present analysis are in good agreement with the experimental data of chill penetrations found in wedge shaped castings. Quantitatively, thi s analysis predicts that small sulphur additions impede the growth of graphite eutectic cells while raising the degree of undercooling in ca st iron.