This paper describes the development of a thermal model for flashlamp processing of 3C-SiC on silicon substrates. The model is a numerical solution of the enthalpy equation, using a modified implicit Crank-Nicholson scheme to combine accurate prediction of melt depths with reasonable computation times. The model has been calibrated against experiments and then used to compute the temperature distribution in the wafer during annealing. The results show the time and extent of melting of the substrate below the 3C-SiC layer as a function of layer thickness, wafer preheat temperature and pulse intensity and duration. The kinetics of melting and regrowth have also been considered.