Effect of cold work on the mechanical response of drawn ultra-fine gold wire

Effect of cold work on the mechanical response of drawn gold wire is studied using finite element (FE) simulations. The drawing simulations were conducted in a single stage as well as multi-stage, i.e. two steps for the equivalent area reduction on a micrometer size gold wire. The effect of wire drawing process parameters such as die angle, coefficient of friction and area reduction were considered for the simulations. A clear variation in residual stresses from tensile to compressive is seen across the wire cross-section. Mechanical properties are assessed via residual stress state and the hardness variation across the drawn wire cross-section; the hardness is determined using simulated micro-indentation tests. The effect of this stress is also observed in the indentation response. In the area of tensile residual stresses increasing pile-up was seen at the indenter edges, while in the area of compressive stresses the opposite was observed. The results clearly show the dominating role played by the residual compressive and tensile stresses across the wire section in its mechanical response.