Mesomechanical response of microstructure formed on the advancing side of friction stir welded aluminum

The effect of the microstructures observed in different zones of friction stir welded duralumin on the mechanical properties of the alloy is investigated. A dynamic boundary-value problem represented in terms of the plane strain is solved numerically by the finite-difference method. A constitutive model accounting for the elastic-plastic behavior of the material experiencing isotropic strain hardening is built. A fracture criterion allowing for crack nucleation and growth in local regions of maximum equivalent plastic strains is formulated. The disordered polycrystalline microstructure observed in the base material and in the nugget is found to provide a lower strength as compared to the ordered lamellar microstructure of the material in the thermo-mechanically affected zone on the advancing side of the weld.