In car body construction, hot stamping components made of MnB steel are used to increase crash safety. The sheets are heated to 950 °C in natural gas-powered roller hearth furnaces, subsequently transferred to a water-cooled hot forming tool, and formed and hardened into components in a single process. In subproject A04, an alternative heating method is developed in which the sheets are heated to target temperature within seconds by introducing an electric current. This resistance heating method can reduce the energy needed by more than 70 %. Additionally, the process completely suppresses undesirable scale formation by using a silane-doped protective gas atmosphere ("XHV- adequate "). One trend is the adaptation of material properties. The necessary increase in strength is associated with a loss of ductility. In order to increase the latter, various concepts are employed on the material or process side, all of which are associated with a loss of strength. The goal of the transfer project is to increase the performance of hot stamped MnB steels by simultaneously increasing strength and ductility. This is to be achieved in an XHV-adequate atmosphere by the combination of ductility-enhancing surface layer decarburization of the MnB steels and resistance heating. The ductility-enhancing surface layer does not oxidize and at the same time strength-reducing significant grain growth in the material is avoided. Both together should lead to the maximum possible increase in performance.
