What is P20 Steel ?
AISI P20 Steel Plate Material is a versatile, low-alloy tool steel that is characterized by good toughness at moderate strength levels. The special purpose mold steel P20 steel plate is commonly used for plastic injection mold cavities and tooling and for die casting dies for zinc. P20 mold steel plate material is typically sold in the pre-hardened condition at a hardness of approximately 300 HBW.
P20 tool steel differs from area to area in the different countries.Europeans generally use the DIN spec-DIN EN ISO 4957 standard materials (1.2311 and 1.2312), while in Japan steel industry standard, PX5 is the new standard P20. And the Americas Countries, Grade steel P20 is the most and wide used steel grade material. In China, 3CrM2Mo is the P20 steel grade equivalent, which is in the standard GB/T 1299 tool steel specification.
AISI P20 tool steels are nitrided or carburized. These P20 mold steel materials steels are capable of being machined into complex and large dies and molds. Material P20 steel plate and round bars are mostly used in the carburized condition. The presence of chromium and nickel enhances the toughness and hardness of mold steel P20 grade material.
1. Supply Range of P20 Steel
Round Bar: diameter 200mm – 1000mm
Steel Plate: thickness 16-800mm x width 200-2300mm
Surface Finish: Black, Rough Machined, Turned or as per given requirements.
2. Relevant P20 Tool Steel Specification and Equivalent Steel Grades
| Country | USA | German | GB/T |
| Standard | ASTM A681 | DIN EN ISO 4957 | GB/T 1299 |
| Grades | P20 | 1.2311 | 3Cr2Mo |
3. AISI P20 Steel Plate Materials
| ASTM A681 | C | Mn | P | S | Si | Cr | Mo | |||||
| P20 | 0.28 | 0.4 | 0.6 | 1 | 0.03 | 0.03 | 0.2 | 0.8 | 1.4 | 2 | 0.3 | 0.55 |
| DIN ISO 4957 | C | Mn | P | S | Si | Cr | Mo | |||||
| 1.2311 | 0.35 | 0.45 | 1.3 | 1.6 | 0.03 | 0.03 | 0.2 | 0.4 | 1.8 | 2.1 | 0.15 | 0.25 |
| GB/T | C | Mn | P | S | Si | Cr | Mo | |||||
| GBT 1299 | 0.28 | 0.4 | 0.6 | 1 | 0.03 | 0.03 | 0.2 | 0.8 | 1.4 | 2 | 0.3 | 0.55 |
4. ASTM P20 Mold Tool Steel Properties
Physical Properties
- Density: 0.284 lb/in3 (7861 kg/m3)
- Specific Gravity: 7.86
- Modulus of Elasticity: 30 x 106 psi (207 GPa)
- Thermal Conductivity:
- 24 Btu/ft/hr/°F
- 41.5 W/m/°K
- Machinability: 60-65% of a 1% carbon steel
P20 Steel Mechanical Properties
| Properties | Metric |
| Hardness, Brinell (typical) | 300 |
| Hardness, Rockwell C (typical) | 30 |
| Tensile strength, ultimate | 965-1030 MPa |
| Tensile strength, yield | 827-862 MPa |
| Elongation at break (in 50 mm (2″)) | 20.00% |
| Compressive strength | 862 MPa |
| Charpy impact (V-Notch) | 27.1-33.9 J |
| Poisson’s ratio | 0.27-0.30 |
| Elastic modulus | 190-210 GPa |
AISI P20 Mold Tool Steel Thermal Properties
| Properties | Conditions | ||
| T (°C) | Treatment | ||
| Thermal expansion | 12.8 x 10-6/ºC | 20-425 | – |
5. Forging of P20 Steel Plate Mold Steel
AISI P20 steel plate and round bars materials are forged at 1093°C (2000°F) down to 899°C (1650°F). Forging below 871°C (1600°F) is not recommended for these steels P20 material.
6. Heat Treatment of Tool Steel P20 material
- Stress Relieving
Preheating: Because mold steel P20 steel plate is sold in a pre-hardened condition, hardening heat treatment is not necessary. After machining and intermittently during service, the steel must be thermally stress relieved by heating to 900ºF (482ºC), equalizing and holding for one hour per inch (25.4mm) of thickness, and cooling in air to ambient temperature.
In those rare circumstances where the AISI steel P20 must be re-hardened, the steel must first be annealed prior to hardening.
- Hardening
Critical Temperature: Ac1: 1405ºF (763ºC)
Preheating of P20 metal: Heat at a rate not exceeding 400ºF per hour (222ºC per hour) to 1150-1250ºF (621-677ºC) and equalize.
- Austenitizing (High Heat)
Heat rapidly from the preheat to 1550ºF (843°C). Soak for 30 minutes for first inch (25.4mm) of thickness, plus 15 minutes for each additional inch (25.4mm).
- Quenching
Pressurized gas, or interrupted oil to 150-125ºF (66-51ºC).
For oil, quench until black, at about 900°F (482°C), then cool in still air to 150-125°F (66-51°C).
- Tempering
P20 tool steels are tempered at 482-593°C (900 to 1100°F) for a Rockwell C hardness of 37 to 28.
- Annealing
Annealing for AISI P20 tool steels takes place at 760-788°C (1400 to 1450°F) and then the steels are cooled slowly in the furnace at a temperature less than 4°C (40°F) per hour.
7. Applications of P20 Steel Plate or Bar
P20 tool steels are used for low temperature applications that include injection molds and die casting dies. Main applications of P20 steel plate and bar:
Plastic moulds, die holder, backers, rames for plastic pressure dies, hydro forming mold tools.bolsters, die holders. Also suitable for other applications such as rails, shafts and wear strips.