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

  • I. Valls
  • B. Casas
  • N. Rodríguez
  • U. Paar

Abstract

Hot stamping is a fairly novel technology where tool steels play a capital role, they strongly influence the
properties of the obtained component, the die has a strong contribution to investment and maintenance costs
and above all, the influence on produced component cost is unusually high. This is so because productivity is
a capital cost factor in this technology, and tool material together with cooling strategy has a great effect on
attainable cycle time. In stationary regime, the heat has to be transported from the produced piece to the
cooling fluid as fast as possible. Here the cooling strategy and even more the tool material thermal
conductivity are the determinant factors, taking for granted that the sheet-tool contact and the cooling fluid
turbulence are sufficient. Moreover the thermal conductivity of the tool material influences the aggressiveness
of the cooling strategy that can be employed, since it’s one of the main determining factors in the thermal
shock 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 simulation
and experimentation. Then several hot work tool steels have been developed with extreme thermal conductivity
and with the wear resistance adapted to every specific sheet coating. In the evaluation of these tool steels it
has been seen that the predicted tool material requirements were indeed the necessary ones.

Published
2010-11-25
Section
Memorie