Heat Flow in the solidification of Casting

A theoretical study has been made of the factors which control the rate of heat flow from solidifying sand and chill castings. The in-vestigation has been focussed on three shapes of high symmetry: spheri-cal, cylindrical, and slab-shaped castings. An evaluation of Chvorinov's Rule for sand castings (freezing time proportional to the ratio, squared, of volume to surface area) indi-cates that this simplified relationship is valid only for comparing castings having similar shapes. More precise expressions are presented for the three basic shapes. For purposes of calculation, it is shown that: (1) Superheat may be accurately added, calorifically, to the latent heat of fusion. (2) Alloys which freeze over wide ranges of temperature, and which evolve their latent heat uniformly over this range, have an "effective " melting point one-fifth of the way from the solidus to the liquidus