Strain rate effect on the deformation and fracture in different zones of friction stir welded aluminum

Deformation and fracture of polycrystalline microstructures typical for different zones of friction stir welds are numerically investigated. A phenomenological physically-based dislocation model is used to describe the dynamic behavior of aluminum. The ordinary differential constitutive equation is solved to determine the model parameter for the Al6061-T6 alloy. Using this equation, two-dimensional calculations are carried out for aluminum specimens subjected to tension at different strain rates, with the polycrystalline microstructure observed in the nugget and thermo-mechanically affected zone on the advancing side of the weld being taken into account in an explicit form. Convergence of the numerical solution is proved. Fracture patterns are shown to depend on the strain rate.Deformation and fracture of polycrystalline microstructures typical for different zones of friction stir welds are numerically investigated. A phenomenological physically-based dislocation model is used to describe the dynamic behavior of aluminum. The ordinary differential constitutive equation is solved to determine the model parameter for the Al6061-T6 alloy. Using this equation, two-dimensional calculations are carried out for aluminum specimens subjected to tension at different strain rates, with the polycrystalline microstructure observed in the nugget and thermo-mechanically affected zone on the advancing side of the weld being taken into account in an explicit form. Convergence of the numerical solution is proved. Fracture patterns are shown to depend on the strain rate.