ALSPEN-A mathematical model for thermal stresses in direct chill casting of aluminum billets

Abstract

This paper presents the mathematical model ALSPEN, in which the thermally induced strains and stresses which develop during direct chill (DC) semicontinuous casting of aluminum billets are calculated by a finite-element method. The metal is assumed to be an isotropic elasticviscoplastic material with strongly temperature-dependent properties. In the material description, the viscoplastic strain is treated in a “unified” manner, in which low-temperature (approximately) time-independent plasticity and creep at high temperatures occur as special cases. Furthermore, in the numerical time stepping procedure, all of these plastic material properties, which are present simultaneously in the solution domain as a result of the large temperature differences, are treated in a similar way. To demonstrate some of the capabilities of ALSPEN, we have modeled the casting of an AlMgSi alloy, AA6063. The material properties of this alloy have been studied in parallel with the development of the mathematical model.