1.2344 forging dies and a 1.2379 forming die
Forging dies
- Material
- 1.2344
- Specified hardness
- 43–45 HRC
- Thickness
- 70 mm
Forming die
- Material
- 1.2379
- Specified hardness
- 56–58 HRC
- Dimensions
- 40 × 40 × 700 mm
- Process
- Vacuum hardening and tempering; the forming die was also stress relieved and sub-zero treated
Process notes
These dies, in 1.2344 hot-work and 1.2379 cold-work tool steel, were heat treated in the Schmetz vacuum furnace. The forming die is extremely sensitive to dimensional change, so flexible thermocouples were placed on the parts with great care, to record the real part temperature during heating and cooling and confirm that the cycle run matched the cycle designed.
Heating was done in steps, with holds at 600 °C and 850 °C, so the microstructure changed gradually and evenly and thermal stress stayed to a minimum. After the hold at the austenitizing temperature of 1030 °C, the parts were quenched with nitrogen gas.
The Schmetz furnace can blow the cooling gas onto the load from two directions, giving a controlled quench in the chosen direction. For tighter dimensional control, the quench intensity was varied at the critical temperatures, following the CCT diagrams of these steels.
After hardening, the hot-work dies were tempered at 525 °C, and the cold-work die was given a mild temper to prepare it for sub-zero treatment at −80 °C. In all, the hot-work dies were tempered three times, and the cold-work die was tempered three times and sub-zero treated.
