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The fatigue of aluminum alloys takes place on several scales, from crack incubation until the failure of the structure. Fatigue cracks generally form along either grain boundaries or at particle inclusions in the microstructure. In order to capture these fatigue crack nucleation mechanisms micromechanical polycrystalline models have been developed. It is not computationally feasible to model the entire structure under consideration with a polycrystal model. Therefore, only the subdomains where a dominant fatigue crack is likely to nucleate will be modeled using micromechanics. Modeling certain subdomains as a continuum and others as a microstructural polycrystal necessitates coupling the two scales together. A multiscale procedure, within a finite element context, is developed for combining a continuum scale model with a polycrystalline microstructure model, designed to represent crack nucleation mechanisms of aluminum alloy. The multiscale procedure is derived from classical multigrid methods to couple the two scales of interests. Using the variational multiscale finite element method as a guide the polycrystal model is embedded into the structural model through constitutive parameters. This has the effect of coupling the two models together as if they were one model. The resulting nonlinear problem is solved using a multigrid based method. The procedure provides results useful for studying the fatigue lifetime of metallic structures