This article documents a series of physical direct chill casting simulations performed on specimens of an AA3103 alloy by means of a Gleeble machine. During the experiments the specimens are subjected to thermal and straining histories similar to those experienced by material points in an ingot during the casting process due to thermal stresses. The measured stress is compared to the stress given by a steady-state creep law for the measured temperature and strain rate versus time. The creep law gives a good fit for temperatures above 400oC but increasingly overestimates the stress level as the temperature decreases below this level because of the increasing importance of work hardening. Since thermally induced straining occurs in the entire temperature interval in the casting process, it is concluded that more sophisticated constitutive modeling than the creep law is needed.