Introduction
1.2311 (Reference standard UNI EN ISO 4957) steel is one kind of hardened and tempered condition, it is equivalent to AISI P20 tool steel.
Smelting method : EAF+LF+VD+ESR
Main Characteristics : Steel with excellent hardening penetration up to 400mm. Generally supplied in hardened and tempered condition with excellent polishing and photoengraving properties. This steel is suitable for nitriding (around 800 HV), chrome and nickel plating.
Major Applications : Used for plastic dies with excellent surface finish properties. It is also used for dies of light alloys with low melting point, plates, dies box etc.
Chemical Composition : (%)
| C | Si | Mn | Cr |
|---|---|---|---|
| 0.35-0.45 | 0.20-0.40 | 1.30-1.60 | 1.80-2.10 |
| Mo | Ni | P | S |
|---|---|---|---|
| 0.15-0.25 | - | ≤0.030 | ≤0.030 |
Comparable Standards : (%)
| UNI | W.Nr | DIN |
|---|---|---|
| - | 1.2311 | X40CrMnMo7 |
| AFNOR | AISI/SAE | BS |
|---|---|---|
| 40 CMD8 | P20 | P20 |
Critical Points :
| Ac 1 | 740°C |
|---|---|
| Ms | 310°C |
Supply Conditions : Hardened and Tempered Normal HB 280-325 (950-1100N/mm²)
Heat Treatments :
Annealing :
- Heat to 720-750℃, for 2-4 hour furnace cool.
Stress relieving :
- Upto 560-600℃, hold for 2-4 hour
- Furnace or steel air cooling
Hardening :
- Preheating to 600-650℃
- Heat to hardening temperature to 840-870℃ and hold at temperature
- Cooling in oil
- Hardness after hardening 51 HRC
Tempering :
- To be carried out soon after the hardening in the range 580-650℃ for 1 hour for 25mm of thickness minimum 2 hour.
