Hot stamping: manufacturing functional optimized components

Due to rising requirements regarding passenger safety and weight reduction hot stamped components get more and more important regarding security relevant parts because of their high strength. Currently, the new challenge is manufacturing components with locally adjusted mechanical properties in order to simultaneously guarantee structural integrity and energy absorption in case of a crash. Therefore, the so called Tailored Tempering process is a promising strategy controlling the cooling rate of the austenitized blank by local heating of the tool and consequently adjusting microstructure development and resulting mechanical properties. As the adjustment of mechanical properties is a temperature dependent process which is also influenced by process parameters and contact conditions, accurate process knowledge is essential. Within this paper the influence of tool temperature and applied contact pressure on the resulting heat transfer coefficient as well as contact condition between the surfaces of former investigations will be shown in a short overview. Based on the results of these fundamental investigations, design principles for Tailored Tempering process will be derived. Furthermore, a hat-profile geometry will be investigated experimentally and characterized by mechanical tests as well as geometrical aspects like sheet thickness and distortion. Additionally, an FE-Modell based on the results of the thermo-mechanical characterization is build up and validated by comparison with the results of experimental work.