Micro wire-drawing: Experiments and modelling

In the paper, the authors propose to adopt the micro wire-drawing as a key for investigating models of micro forming processes. The reasons of this choice arose in the fact that this process can be considered a quasi-stationary process where tribological conditions at the interface between the material and the die can be assumed to be constant during the whole deformation. Two different materials have been investigated: i) a low-carbon steel and, ii) a nonferrous metal (copper). The micro hardness and tensile tests performed on each drawn wire show a thin hardened layer (more evident then in macro wires) on the external surface of the wire and hardening decreases rapidly from the surface layer to the center. For the copper wire this effect is reduced and traditional material constitutive model seems to be adequate to predict experimentation. For the low-carbon steel a modified constitutive material model has been proposed and implemented in a FE code giving a better agreement with the experiments.