P20
1.2311 / 40CrMnMo7 · EN ISO 4957 · 1.2311
P20 (1.2311 / 40CrMnMo7) is a tool steel (Plastic Mould family) to EN ISO 4957 (1.2311). It has a specified 0.2 % proof stress of 900 MPa and a typical tensile strength of about 1100 MPa, with a uniform elongation of 12 %. Nominal carbon content is around 0.35 %. For nonlinear FEA, a bilinear model uses E = 210 GPa up to yield and a tangent modulus of 1759 MPa above it. It is formulated for hardness, wear resistance and dimensional stability in tooling.
Bilinear material model — nonlinear FEA
Uniform elongation εu = 12.0% · conservative analysis limit ½εu = 6.0%
Bilinear (BISO) approximation. Elastic modulus E up to the 0.2% proof stress R_p0.2, then a single tangent slope Eₜ to the ultimate tensile strength: Eₜ = (Rₘ − R_p0.2) / (εu − R_p0.2/E − 0.002), where εu is the uniform elongation and Rₘ is a typical (nominal) UTS within the specified band. The half-εu figure is a conservative strain limit for the analysis. Treat these as guidance for first-pass models; for critical work use a measured true stress–strain curve for the actual product and condition.
Ratings — engineering judgement
Weldabilitymoderate
Medium carbon (~0.35%) — preheat and hydrogen-controlled consumables advisable, especially in thicker sections.
Machinabilitypoor
Machine in the annealed condition; hard and abrasive once heat treated.
Corrosion resistancepoor
No inherent corrosion resistance — protect by paint, galvanising or plating in exposed use.
Hardenabilityexcellent
Designed to through-harden to high hardness for wear and cutting duty.
Toughnesslow
Hard and wear-resistant but low toughness — not for shock loading unless a shock-resisting grade.
Indicative ratings derived from composition and family — engineering guidance, not specification values.
Physical properties
| Density | 7800 | kg/m³ |
| Elastic modulus | 210 | GPa |
| Shear modulus | 80.8 | GPa |
| Poisson's ratio | 0.30 | |
| Thermal expansion | 11.5 | ×10⁻⁶/°C |
| Thermal conductivity | 30 | W/(m·K) |
| Specific heat | 460 | J/(kg·K) |
| Magnetic | Yes |
Typical values for plastic mould steel — use the mill certificate for the specific product.
Chemical composition (wt %)
Nominal composition per EN ISO 4957 for P20 — confirm exact limits against the standard.
Available forms
Common applications
- Cutting, forming and blanking tools
- Dies, punches and moulds
- Wear parts and gauges
History
The cold- and hot-work tool steels are high-carbon, high-alloy steels formulated for hardness, wear resistance and dimensional stability in cutting, forming and die work. The family runs from simple oil- and water-hardening grades to the high-chromium and hot-work die steels.
- 1868Robert Mushet’s self-hardening tungsten tool steel — the ancestor of alloy tool steels
- 1920High-chromium (D-series) cold-work and Cr–Mo hot-work die steels developed
- 1998EN ISO 4957 harmonises the European tool-steel grades
This profile is generated from the grade's core data and family. Composition is decoded from the designation where its naming system defines it; physical properties are family-typical and ratings are indicative. Confirm critical values against the governing standard or the mill certificate. Equivalents, historical designations and hand-written expert notes are added per grade over time.