EFFECT OF THERMAL CAPACITY ON THERMOELASTIC INSTABILITY DURING THE SOLIDIFICATION OF PURE METALS

Abstract

If unidirectional solidification of pure metals at constant cooling rate is perturbed by a small spatially sinusoidal heat flux at the casting / mold interface, corresponding responses with sinusoidal perturbation are obtained for the evolution of the casting / melt interface, for the temperature and stress fields in the solidified casting and for the contact pressure at the mold surface. The results show that the perturbation in contact pressure tends asymptotically to a maximum value at larger values of time. The magnitude of the contact pressure perturbation is decreased by the inclusion of thermal capacity, and this effect is enhanced at higher mean cooling rates. This indicates that materials with higher specific heat (or lower thermal diffusivities) might be less susceptible to thermoelastic instabilities associated with the contact pressure and its dependent thermal contact resistance at the casting / mold interface.