The development of grain structure during Vacuum Arc Remelting (VAR) of INCONEL1 alloy 718, a nickel-based superalloy, is complex depending both on compositional variations and a range of process parameters. A multiscale model is presented which combines a macroscopic solution of the heat transfer, fluid flow and electromagnetism with a mesoscopic model of grain nucleation and growth. The model was used to investigate the influence of variations in process control parameters upon the macroscopic molten pool size and shape, together with the predicted grain structure. Simulations of structures produced for variations in melt rate, arc power and arc focus (both thermal and electrical) were compared with observations from instrumented and characterized plant-trials for steady state melting conditions; good agreement was achieved. (C) 2004 Kluwer Academic Publishers.