ORIGINAL ARTICLE Failure analysis of a cold work tool material slides against carbon steel in sheet metal forming process — A case study of hinges production Wissal Yangui 1 & Noamen Guermazi 1 & Khaled Elleuch 1 Received: 23 February 2016 /Accepted: 6 June 2016 # Springer-Verlag London 2016 Abstract In general, the contact conditions between the tool and the workpiece materials in sheet metal forming process are always of high industrial importance since it permits to enhance the tool life. The present work focuses on the sliding metallic contacts taking place in the case of the manufacturing of hinges. A case study has been conducted on the cold plastic rolling (CPR) tool and the hinges in the CPR process. An expertise of CPR die active part and hinge surface was carried out in order to identify and to analyze the failure mechanisms. Several techniques were used such as profilometry, energy dispersive spectroscopy (EDS), optical and scanning electron microscopy (SEM). The failure mechanisms of the tool and the hinge were studied during various cycles of manufactur- ing. The failure of the CPR die active part was found to be related to the transfer of fragments from the hinge material and then their accumulation on the tool surface, generally referred to galling. The failure mechanisms of the hinge material were found to depend on the number of manufacturing cycles. At first and intermediate stages, fine and large scratchings were produced on the curved surface of the hinge, respectively. At later stages, a back transfer of sheet fragments to the hinge surface takes place by severe scratchings. Keywords Cold work tool . Metal forming . Failure analysis . Wear . Galling 1 Introduction Sheet metal forming is a deformation of sheet material into a shape without material removal. The sheet metal must be characterized by its high ductility and various ranges of mechanical strength. On the contrary, the tool material must be chosen to present high hardness, good wear resistance, and adequate toughness. Moreover, since sheet metal forming tools represent high economical value and because change of tooling causes standstill in produc- tion, it is evident that the tool life is usually of high im- portance for industries even for academics. Here, great efforts have been devoted to highlight the causes of sur- face damages of the workpiece as well as of the tool material [1–5]. From literature review [2, 3], it was report- ed that the sliding between two materials in dry contact often induces a mechanism of galling. According to Ref. [5], under high load, the softer material (workpiece mate- rial) adheres locally to the tool surface forming hard “galls” which lead to the wear. In particular, during re- peated forming, the major failure is the workpiece and tool damages by galling. As reported in Ref. [3], galling is a wear process associated with the tendency for lubri- cant film breakdown resulting in pick-up of sheet material by the tool surface and severe scratching of the workpiece surface. Large research done on the tribological contacts * Noamen Guermazi noamen.guermazi@enis.tn Wissal Yangui wissal.yangui@yahoo.fr Khaled Elleuch khaled.elleuch@enis.rnu.tn 1 Laboratoire Génie des Matériaux et Environnement (LGME), Ecole Nationale d’Ingénieurs de Sfax (ENIS), Université de Sfax, B.P. 1173-3038, Sfax, Tunisia Int J Adv Manuf Technol DOI 10.1007/s00170-016-9015-4