Enhanced Ductility in Sheet Metals Produced by Cladding a Ductile Layer

The effect of cladding a ductile layer on necking and fracture in sheet metals under plane strain tension is studied numerically using the finite element method based on the Gurson damage model. It is demonstrated that the cladding increases both the necking and fracture strains. The increase in necking strain is due to the fact that cladding a ductile layer enhances the overall work hardening for the layered metal sheets according to the rule of mixtures. Furthermore, the increase in necking strain slows down the development of the triaxial tensile stress inside the neck, which delays the void nucleation and growth, and which, in turn, contributes to enhancement in ductility.