Summary : This thesis deals with the numerical simulation of cold forming processes, i.e. wire drawing and rolling. First, high carbon steel mechanical behaviour was measured from experiments throughout this range of steel forming and a progressive mechanical anisotropy has been observed during drawing. Secondly, numerical simulations, with FORGE2005®, have been run to simulate the material behaviour during wire drawing and rolling. The main results show that the widening prediction, with an isotropic behaviour law, is not accurate with an underestimation of 10% on the total width. This underestimation is only 5% when an anisotropic behaviour is used. Then, a microstructural study coupled with an analysis of damage mechanisms was done on high carbon pearlitic steels during wire drawing and rolling. The mechanical anisotropy comes from the orientation of the pearlitic colonies in the drawing, and by the emergence of a preferential crystallographic texture. Three damage mechanisms have been identified during drawing. During rolling, damage expansion kinetics are changed because of heterogeneous strain. Simulation enabled to bring further information and to validate previous experimental observations. Finally, drawing optimization calculations have been performed and enabled to study the sensitivity of the cost functions (damage and drawing force) to optimization parameters (drawing die geometry). Moreover this study highlighted that optimal solution depends on the choice of the cost function and identified an opportunity to reduce damage by reducing the die angle without increasing the axial stresses and the fracture risk.