Einfluss der Temperatur und des Vergütungszustands auf die Wärmeleitfähigkeit von Warmarbeitsstählen für das Presshärten

Press hardening is used to produce automotive blanks with high tensile strength. In order to gain optimal blank properties it is necessary to rapidly decrease the blank temperature during press hardening. The thermal conductivity of the hot work tool steel used for die material is an important factor that defines the process time and the resulting blank properties. This study investigates the influence of temperature, alloying composition and heat treatment on the thermal conductivity of hot work tool steels used for press hardening dies. The dynamic method is used to determine the thermal conductivity of the hot work tool steels via an indirect measurement. The thermal conductivity decreases with increasing amount of alloying elements. In the temperature range between 295 and 473 K, which is the relevant temperature range for press hardening applications, the thermal conductivity of the hot work tool steels increases with temperature independent of the thermal treatment. With further increase of the temperature above 473 K the thermal conductivity of the hot work tool steels decreases.