Chair of Physics and Chemistry of Cast Alloys and Processes, Saint-Petersburg State Polytechnical University (Saint-Petersburg, Russia):

Golod V. M., Cand. Eng., Prof.

Emelyanov K. I., Post-graduate

Orlova I. G., Post-graduate

E-mail (common): cheshire@front.ru

The paper reviews the publications concerning the dependence of dendrite arm spacing of iron-based industrial alloys from the conditions of solidification. It was noted that the used thermal parameters which characterize the conditions of dendrite formation — the rate of solidification, the temperature gradient and the cooling rate, — are determined quite often with significant experimental errors, are estimated on the basis of approximate relationships and often mutually correlated. It was established that the published empirical power-type models of dendrite arm spacing for carbon and low-alloy steels are characterized by a lot of the type of the parameters-predictors and by scatters of their values, and do not consider the effect of the alloys composition and therefore are slightly suitable for prediction of the dendritic structure. For objective assessment of uncertainties arising from the use of insufficiently large data sets and simplified method of estimation for model parameters, the procedures of statistical analysis of the models adequacy for their correction and/or rejection were proposed. The comparison of results of computer simulation for steel slabs (250 mm in thickness) with 0.006, 0.06 and 0.6% C content are used for analysis of the evolution of the rate of crystallization and the temperature gradient under various intensity of heat extraction and natural convection of the melt during solidification. It was deduced that a radical increase of the analysis accuracy for the conditions of formation of the dendritic structure is provided by usage of the deve loped computer model of non-equilibrium solidification of ingots and castings on the base of thermal properties of alloys. It is shown that these properties are determined by means of thermodynamic simulation, with obligatory taking into account the intense convective heat transfer in the melt.

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