Thermo-Mechanical Model of Solidification Processes with Abaqus

A computational thermo-mechanical model has been developed to simulate the continuous casting of shaped sections, such as used for thin steel slabs. A general form of the transient heat equation including latent-heat from phase transformations such as solidification and other temperature-dependent properties is solved numerically for the temperature field history. The resulting thermal stresses are solved by integrating the highly nonlinear thermo-elastic-viscoplastic contitutive equations using a two-level method. The procedure has been implemented into Abaqus, (Abaqus Inc., 2005) using a user-defined subroutine (UMAT) to integrate the constitutive equations at the local level (Koric, 2006). The model is validated both with a semi-analytical solution from Weiner and Boley (Weiner, 1963) as well as with an in-house finite element code CON2D (Li, 2004, Zhu, 1993) specialized in thermo-mechanical modeling of continuous casting. The model is applied to simulate a 3D segment of the solidifying steel shell as it moves down through a thin slab caster with a funnel mold, known for its complex geometry, using realistic operating conditions and temperature-dependant properties. It has provided valuable new insights into the complex dynamic 3D mechanical state of stress experienced by the solidifying shell due to the funnel geometry.