August 2022 Volume 4

MATERIALS

One of our more recent alloys, HSF is a five-percent CrMoV steel. This premium steel offers a good toughness that allows it to be used at higher working hardnesses, thus increasing wear resistance. With its high carbon content, the steel offers high tempering resistance and can thus withstand high temperature loads for a long time. This steel is an excellent choice for warm forging. It is particularly in demand for applications with high requirements for hot wear resistance. Another recently developed alloy, LMF, offers a material concept tailored to the growing requirements of finisher dies. While finisher dies are subjected to slightly lower thermal and abrasive stresses than blocker dies, they have higher requirements to meet tight forging tolerances. LMF is the economical solution for finisher dies, providing good wear resistance with high toughness and improved tempering resistance.

The general character of a hot-work tool steel is defined by its chemical composition, but the metallurgical melting technologies, the forging process and the heat treatment applied at the steel mill drastically influence the property profile of a die steel. By optimizing these parameters the best combination of properties for the designated application can be achieved. Forging dies are subject to various stresses during use. The thermal load on the dies plays a particularly important role. Nevertheless, the most frequent cause of failure is die wear.The choice of the right hot work tool steel for forging tools is essentially a matter of finding the best compromise between toughness, wear resistance and resistance to thermal fatigue. References: (1) Schruff, I.: Der Einfluss des Werkzeugstahles auf den Werkzeugverschleiß beim Gesenkschmieden; Tribologie und Schmierung bei der Massivumformung, expert Verlag, S. 121-139, Renningen, 2004 Philipp Görts, M.Sc Kind & Co. Edelstahlwerk, GmbH& Co. KG

Figure 1: Comparison of different hot-work tool steels

FIA MAGAZINE | AUGUST 2022 35