Steel P20 Prehard-Nitrided
Finish state
AISI/SAE P20 · UNS T51620 · EN 1.2311, 40CrMnMo7 · GB 3Cr2Mo
Use for abrasive or glass-filled resins: hard nitrided case (0.1–0.3 mm) on the 28–34 HRC core improves wear and corrosion slightly.
Values for the Prehard-Nitrided condition
Other P20 tempers and conditions
P20 is listed in 4 conditions; see the grade overview at P20.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault soft annealed, ~180–220 HB | Choose when the part will be rough-machined and then through-hardened, or for deep hot-work/EDM-free forming of blocks. | 440 | 700 | 20 | 200 HB | — |
Pre-hardened | Default stock condition: machine the cavity directly, no post-machining heat treatment or distortion risk. | 860 | 1,000 | 15 | 31 HRC | — |
Prehard-NitridedThis page pre-hardened core with gas/plasma nitrided case | Use for abrasive or glass-filled resins: hard nitrided case (0.1–0.3 mm) on the 28–34 HRC core improves wear and corrosion slightly. | 860 | 1,000 | 13 | 31 HRC | 7.8 % IACS |
Quenched and tempered | Pick when higher wear resistance and cavity-face hardness than pre-hardened stock is needed; accept quench distortion and finish-grinding. | 1,150 | 1,350 | 11 | 42 HRC | — |
What is P20 Prehard-Nitrided?
P20 Prehard-Nitrided is P20 supplied in the Prehard-Nitrided condition — use for abrasive or glass-filled resins: hard nitrided case (0.1–0.3 mm) on the 28–34 HRC core improves wear and corrosion slightly. P20 Prehard-Nitrided has a yield strength of 860 MPa (125 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 89% of steel grades. Elongation at break is 13% and the elastic modulus is 205 GPa (29.7 Msi). P20 Prehard-Nitrided has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,420°C (2,588 °F). Annealed is the default condition FabDigit quotes; Prehard-Nitrided is available on request or by drawing note.
Advantages
- Good corrosion resistance — 25/100, better than 92% of steel grades
- High strength — 860 MPa (125 ksi), better than 89% of steel grades
- High service temperature — 450°C (842 °F), better than 86% of steel grades
Limitations
- Difficult to machine — 10/100, worse than 99% of steel grades
- Difficult to weld — 10/100, worse than 99% of steel grades
- Limited formability — 5/100, worse than 99% of steel grades
- Poor heat conductor — 32 W/m·K (18.5 BTU/hr·ft·°F), worse than 82% of steel grades
- Limited ductility — 13%, worse than 78% of steel grades
P20 Prehard-Nitrided properties
Typical room-temperature values for P20 Prehard-Nitrided; 22 are specific to this condition. Other listed values are P20 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
P20 Prehard-Nitrided has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical17
P20 Prehard-Nitrided has a yield strength of 860 MPa (125 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 89% of steel grades. Elongation at break is 13% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
P20 Prehard-Nitrided is rated for continuous service to 450°C (842 °F). It conducts heat at 32 W/m·K (18.5 BTU/hr·ft·°F), worse than 82% of steel grades. Thermal expansion is 12.4 µm/m·K (6.89 µin/in·°F).
Electrical2
P20 Prehard-Nitrided has an electrical resistivity of 2.2×10⁻⁷ Ω·m.
Chemical & Environmental3
Corrosion resistance is poor (25/100), better than 92% of steel grades.
Sustainability4
Producing a kilogram of P20 Prehard-Nitrided takes about 32 MJ of energy and emits 2.2 kg of CO₂ — more than 70% of steel grades. Typical recycled content is 40%.
Manufacturability7
P20 Prehard-Nitrided's machinability is not recommended (10/100, worse than 99% of steel grades); weldability not recommended (10/100); formability not recommended (5/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with P20 Prehard-Nitrided
Is P20 easy to machine?
Machines predictably at 28–34 HRC with coated carbide (vc ≈ 120–180 m/min milling); rigid setups and positive rake reduce work-hardened burr, and stress-relieve at 550 °C after heavy roughing of deep cavities.
Can P20 be welded?
Repair-weldable with matching low-alloy or 1.2311-type filler using 300–350 °C preheat, low heat input and immediate 500–550 °C post-weld temper to avoid HAZ cracking.
Can P20 be formed, bent or molded?
Not a cold-forming steel; shape by hot forging at 1050–850 °C followed by slow cooling and soft annealing, or by machining/EDM in the pre-hardened state.
What surface finishes work on P20?
Polishes to mirror finish (best from ESR/VAR remelted plate); typically hard-chrome plated, electroless-nickel plated or nitrided/texture-etched for mold cavities, and must be oiled to prevent rust.
P20 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| C1.2311 typically 0.35–0.45 | 0.28 – 0.4 | 0.35 |
| Si | 0.2 – 0.8 | 0.4 |
| Mn | 0.6 – 1 | 0.8 |
| Cr | 1.4 – 2 | 1.7 |
| Mo | 0.3 – 0.55 | 0.4 |
| P | ≤ 0.03 | — |
| Smax; free-machining variant 1.2312 has S 0.05–0.10 | ≤ 0.03 | — |
| Niresidual; P20+Ni (1.2738) adds ~1.0 Ni for large blocks | ≤ 0.3 | — |
| Fe | balance | — |
P20 Prehard-Nitrided — frequently asked
What is P20 Prehard-Nitrided used for?
P20 Prehard-Nitrided is typically used for plastic injection mould cavities and cores, mould bases and bolster plates, die-cast mould frames, extrusion dies and die plates, blow-mould bodies and large textured automotive trim cavities. In short: pre-hardened plastic mold.
What is the yield strength of P20 Prehard-Nitrided?
P20 Prehard-Nitrided has a typical yield strength of 860 MPa (125 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 89% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is P20 Prehard-Nitrided easy to machine?
Not especially — machinability is rated not recommended (10/100, worse than 99% of steel grades). Machines predictably at 28–34 HRC with coated carbide (vc ≈ 120–180 m/min milling); rigid setups and positive rake reduce work-hardened burr, and stress-relieve at 550 °C after heavy roughing of deep cavities.
Can P20 Prehard-Nitrided be welded?
Not readily — weldability is rated not recommended (10/100). Repair-weldable with matching low-alloy or 1.2311-type filler using 300–350 °C preheat, low heat input and immediate 500–550 °C post-weld temper to avoid HAZ cracking.
What surface finishes work on P20 Prehard-Nitrided?
Polishes to mirror finish (best from ESR/VAR remelted plate); typically hard-chrome plated, electroless-nickel plated or nitrided/texture-etched for mold cavities, and must be oiled to prevent rust.
Can P20 Prehard-Nitrided be formed, bent or molded?
Not a cold-forming steel; shape by hot forging at 1050–850 °C followed by slow cooling and soft annealing, or by machining/EDM in the pre-hardened state.
What is the maximum service temperature of P20 Prehard-Nitrided?
P20 Prehard-Nitrided is rated for continuous use to about 450°C (842 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between P20 Annealed and P20 Prehard?
Annealed is the default condition — choose when the part will be rough-machined and then through-hardened, or for deep hot-work/EDM-free forming of blocks. Prehard: default stock condition: machine the cavity directly, no post-machining heat treatment or distortion risk. Yield strength is 440 MPa in Annealed versus 860 MPa in Prehard.
Can FabDigit make parts in P20 Prehard-Nitrided?
Yes — P20 Prehard-Nitrided is available for CNC machining with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM A681 – Alloy Tool Steels (Type P20) — ASTM International (2015)
- GB/T 1299 (3Cr2Mo) — SAC (2014)
- EN ISO 4957 Tool steels (40CrMnMo7 / 1.2311) — CEN (2018)
- ASM Handbook Vol.1 – Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.16 – Machining — ASM International (1989)
- Mold steel 1.2311 / P20 datasheet (physical & mechanical data, prehardened) — European tool-steel producers (Böhler / Buderus-type data) (2022)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.