Benefits from using high thermal conductivity tool steels in the hot forming of steels

Hot stamping is a fairly novel technology where tool steels play a capital role, they strongly influence theproperties of the obtained component, the die has a strong contribution to investment and maintenance costsand above all, the influence on produced component cost is unusually high. This is so because productivity isa capital cost factor in this technology, and tool material together with cooling strategy has a great effect onattainable cycle time. In stationary regime, the heat has to be transported from the produced piece to thecooling fluid as fast as possible. Here the cooling strategy and even more the tool material thermalconductivity are the determinant factors, taking for granted that the sheet-tool contact and the cooling fluidturbulence are sufficient. Moreover the thermal conductivity of the tool material influences the aggressivenessof the cooling strategy that can be employed, since it’s one of the main determining factors in the thermalshock resistance. The tribological behaviour of the tools is strongly dependant on the sheet coating employed.AAAIn this work the requirements on press hardening dies have been precisely determined through simulationand experimentation. Then several hot work tool steels have been developed with extreme thermal conductivityand with the wear resistance adapted to every specific sheet coating. In the evaluation of these tool steels ithas been seen that the predicted tool material requirements were indeed the necessary ones