In this paper, results from LS-DYNA numerical simulations are presented with respect to the interfacial morphology of an impact weld of dissimilar sheet materials, i.e., Cu110 (flyer) and CP-Ti (base), both 1 mm thick. These materials were selected as the workpieces since vortices are known to occur at the interface during experimental welding of this material combination. But a conventional Lagrangian numerical method is not capable of capturing this phenomenon due to large element distortions at the interface. Thus, a numerical simulation with the Eulerian method was used to investigate this local, large plastic deformation of materials at high strain rate. Unlike the Lagrangian method, the surrounding air is modelled in the Eulerian method, with a 5 by 5-micron element size in this research, to capture the vortices at the interface. A Johnson-Cook material model, which is widely used for deformation processes at high strain rates, was used for both flyer and base workpieces. Also, a Mie-Grueneisen’s equation of state (EOS) was defined to describe the variation in pressure based on the dynamic condition of materials.