Longer tool life and reduced cycle times in production: press hardening has numerous advantages for the automotive industry, specifically in body part manufacturing. To benefit from the advantages of press hardening in the long term and to further reduce its cycle times, the crucial part of the tool – the mould insert – must be made of a high-strength tool steel that additionally allows for an increase of quenching speed.
It is precisely for this application that Deutsche Edelstahlwerke (DEW), a company of the SCHMOLZ + BICKENBACH Group, developed the hot work tool steel Thermodur 2383 Supercool.
Thermodur 2383 Supercool combines excellent mechanical properties and wear resistance with outstanding thermal conductivity. These properties make the material ideal for use in press hardening tools.
Press hardening, also referred to as hot stamping, is an innovative hot forming process for the production of high-strength body parts. Thus, a preferable ratio of strength to weight can be adjusted, which is equivalent to lightweight construction of car bodies using steel instead of more expensive light metal alloys. The sheet metal part is hot-formed and heat treated in a single, combined process step. Steel sheets are heated to austenitizing temperature and subsequently transferred into a press tool featuring active cooling.
Thus, quenching and forming are performed simultaneously. In addition to good mechanical properties like strength, through hardenability, and wear resistance, thermal conductivity of the tool steel used for this process is of crucial importance for the uniformity of quenching as well as the cycle time and thus the cost-effectiveness of press hardening.
Good thermal conductivity, tensile strength and through-hardening
Compared to conventional hot-work steels (1.2343, 1.2344, and 1.2367) in quenched and tempered condition, the special steel solution Thermodur 2383 Supercool (45 HRC) exhibits a significantly higher thermal conductivity of 44 W/(mK) at 100 °C. A die insert made of this special steel is thus able to conduct heat from the heated sheet in a controlled manner within a very short time.
In addition, it is more resilient at consistently high temperatures, which is expressed by the lack of significant loss of hardness. Combined with an excellent resistance to thermal shock, this may also contribute to endurance of tools made from Thermodur 2383 Supercool even in severely demanding environments.