This thesis is an introduction to ductile failure in sheet metals. First an overview of the main models existing in the literature is given, then examples of applications are provided to illustrate how a damage model can be actually applied to industrial processes. A procedure to identify the parameters of a constitutive and damage model starting from tensile tests and full-field measurements is detailed. The damage model, implemented in a FE code, is used to predict failure in sheet and tube hydroforming processes. The possibility of using numerical tools to predict plastic instabilities such as bursting or wrinkling is also discussed. Finally, in order to show a different way of tackling the problem of ductile fracture, a theoretical and experimental study is conducted about piercing of sheet metals with pyramidal weapons.