1.2311 (40 CrMnMo 7)

AISI P 20

Plastic mould steel for medium and large moulds. Because this material is supplied pre-tempered to 950 - 1,150 N/mm², it is likewise suitable for general machine building components. By comparison, 1.2312 is easier to machine due to the sulphur content but does not polish. 1.2311 can be polished and photo-etched. Both materials can be gas and bath nitrided.

Tempering diagram
Hardness temperature: 850°C
Sample cross section: rect. 50 mm

Surface treatment
Nitriding:
Hardening development in the nitrided case
—— Gas nitriding in amonia stream: 50 hours at 520°C
––– Bath nitriding (Tenifer process) 2 hours at 570°C

TTT diagram for continuous cool down

Austenitisation temperature: 840°C
Dwell time: 15 minutes

Microstructure mass diagram
—— Water cooling
------- Oil cooling
– • – Air cooling

1...Work piece edge
2...Work piece centre
3...Jominy sample: distance from the front face