Explicit coupled thermo-mechanical finite-element model of continuous casting of steel in funnel molds

A three-dimensional transient explicit finite-element method is applied to simulate the coupled and highly-nonlinear thermo-mechanical phenomena that occur during steel solidification in continuous casting of thin slabs in a funnel mold. Variable mass scaling is used to efficiently model the phenomena in their natural time scale using a Lagrangian formulation. The model features an efficient and robust local-global viscoplastic integration scheme to solve the elastic-viscoplastic constitutive equations of solidifying steel [1], using a VUMAT subroutine in ABAQUS/Explicit [2], which varies greatly with temperature, strain rate, steel phase, and composition. The model is applied to simulate temperature and stress development in typical repeating segment of the solidifying shell in a continuous casting funnel mold using realistic temperature-dependent properties and including the effects of ferrostatic pressure, narrow face taper, and mechanical contact, and thermal-mechanical coupling through the size of the interfacial gap. Explicit temperature and stress results as well as computational efficiency are compared with the results of an implicit formulation. The explicit formulation shows significant advantages for these large contact-solidification problems on parallel computers.