P20+Ni Plastic Mold Steel
1.2738 / 1.2738 HH
- EN1.2738
- EN40CrMnNiMo8-6-4
- AISIP20+Ni
Widely used plastic mold steel offering uniform hardness across the full section, mirror polishability and good machinability. It differs from 1.2311 and 1.2312 by its nickel addition, which gives better polishability. Standard 1.2738 is supplied at 30–34 HRC; 1.2738 HH (High Hard) at 34–38 HRC.
01Material Properties
- Uniform hardness across the section
- Homogeneous microstructure of adequate cleanliness
- Good polishability
- Good texturing capability
- Weldability
- Good machinability despite pre-hardening
- Good nitriding response
- Recommended working hardness is the delivery hardness
02Applications
- Cores of all plastic injection molds up to A1 surface quality for polymers with less than 10% reinforcement: automotive trim molds, appliance panels etc.
03Heat Treatment
Typical values
- Delivery condition
- Pre-hardened 280–325 HB (HH: 340–390 HB)
- Stress relieving
- 550–600 °C after rough machining; furnace cooling
- Re-hardening
- 840–870 °C, oil → ≈ 50–52 HRC
- Tempering (after re-hardening)
- 550–650 °C → 30–38 HRC
- Nitriding
- 500–550 °C → surface ≈ 600–650 HV
Heat treatment cycle (schematic)
Tempering diagram (approximate)
Values are approximate and for information only; they vary with section size, heat and furnace conditions. Binding values are determined from the manufacturer’s data under laboratory conditions.
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