P20 Tool Steel Round Bar Supplier & Stockist – DIN 1.2311
ASC LLP supplies P20 tool steel round bars, square bars, flat bars and die blocks in pre-hardened condition for plastic moulds and tooling. Our AISI P20 / DIN 1.2311 (40CrMnMo7) bars are supplied to ASTM A681 at about 28–34 HRC, ready to machine without further heat treatment, with mill test certificates and cut-to-size service.
What is P20 Tool Steel?
P20 tool steel is a low-carbon chromium-molybdenum mould steel, classified by AISI as a “P” (plastic mould) grade. It is supplied pre-hardened and tempered to about 28–34 HRC (roughly 280–320 HB), so mould makers can machine cavities directly and put the tool into service without the cost, delay and distortion risk of hardening after machining.
Its balanced chemistry – about 0.35% carbon, 1.7% chromium and 0.4% molybdenum – gives P20 steel uniform hardness through the section, good toughness, good machinability and a surface that polishes and textures well. That is why P20 (1.2311) is the most widely used steel for plastic injection moulds, mould bases and holder blocks worldwide.
Key Features of P20 Tool Steel Round Bar
- Pre-hardened, ready to machine: supplied at about 28–34 HRC, so no hardening is needed after machining – saving time and avoiding distortion.
- Good toughness: resists cracking in large and complex moulds.
- Uniform hardness: consistent through the cross-section in normal bar sizes.
- Good polishability and texturing: suitable for photo-etching and good surface finishes on moulded parts.
- Nitriding and chrome plating: surface hardness can be increased for better wear resistance.
- Weld-repairable: can be repaired by welding with suitable filler, preheat and post-weld stress relief.
Equivalent Grades of P20 Tool Steel
| Standard | Designation |
| AISI / SAE | P20 |
| ASTM | ASTM A681 (Alloy Tool Steel), Grade P20 |
| UNS | T51620 |
| DIN / Werkstoff Nr. | 1.2311 |
| EN ISO 4957 / DIN name | 40CrMnMo7 |
| China GB | 3Cr2Mo |
| Japan (JIS trade grades) | PX5 / similar pre-hardened mould steels |
A nickel-bearing version, 1.2738 (40CrMnNiMo8-6-4), is used for very large blocks – see the comparison below.
Forms of P20 Steel We Supply
- P20 Tool Steel Round Bar – black, peeled or bright, cut to length
- P20 Square Bar and Flat Bar – for mould inserts and plates
- AISI P20 Rods / DIN 1.2311 Rods – smaller diameters for cores and inserts
- P20 Die Blocks and Mould Bases – milled or ground on request
- 1.2311 Forgings – forged rounds and blocks to drawing
Standard and custom sizes are available from stock or mill, with saw-cutting to your required lengths.
AISI P20 (DIN 1.2311) Round Bar Specifications
| Specification | Details |
| Material grade | P20 tool steel (plastic mould steel) |
| Standards | ASTM A681, AISI P20, DIN 1.2311 / EN ISO 4957 40CrMnMo7 |
| UNS | T51620 |
| Shapes | Round bar, square bar, flat bar, die block, forging |
| Supply condition | Pre-hardened & tempered (Q+T) |
| Hardness | 28 – 34 HRC (approx. 280 – 320 HB) |
| Surface finish | Black (as forged/rolled), peeled, bright, ground, milled |
| Production route | Hot rolled or forged |
| Testing | Ultrasonic testing (UT), hardness check |
| Test certificate | EN 10204 3.1 mill test certificate |
Chemical Composition of P20 Tool Steel (ASTM A681)
| Element | Percentage (%) |
| Carbon (C) | 0.28 – 0.40 |
| Manganese (Mn) | 0.60 – 1.00 |
| Silicon (Si) | 0.20 – 0.80 |
| Chromium (Cr) | 1.40 – 2.00 |
| Molybdenum (Mo) | 0.30 – 0.55 |
| Phosphorus (P) | 0.030 max |
| Sulphur (S) | 0.030 max |
| Iron (Fe) | Balance |
DIN 1.2311 (40CrMnMo7) has a very similar analysis: C 0.35–0.45, Mn 1.30–1.60, Cr 1.80–2.10, Mo 0.15–0.25.
Mechanical & Physical Properties of P20 Steel
| Property | Typical Value (pre-hardened) |
| Hardness | 28 – 34 HRC (approx. 280 – 320 HB) |
| Tensile strength | approx. 950 – 1100 MPa |
| Yield strength | approx. 800 – 900 MPa |
| Density | 7.85 g/cm³ |
| Modulus of elasticity | approx. 207 GPa |
| Machinability | Good (about 60–65% of a 1% carbon tool steel) |
| Toughness | Good |
| Wear resistance | Moderate (improved by nitriding) |
Values are typical for pre-hardened P20 and depend on section size and exact hardness.
P20 vs 1.2738 (P20+Ni) vs OHNS Steel
| Property | P20 / 1.2311 | 1.2738 (P20 + Ni) | OHNS (O1 / 1.2510) |
| Supply condition | Pre-hardened 28–34 HRC | Pre-hardened 28–34 HRC | Annealed – must be hardened |
| Nickel | None | approx. 1% | None |
| Best section size | Small to medium moulds | Large and very thick blocks (more uniform core hardness) | Small tools |
| Toughness | Good | Better | Moderate |
| Wear resistance | Moderate | Moderate | High (after hardening, 57–62 HRC) |
| Typical use | Injection moulds, mould bases, holders | Large automotive and appliance moulds | Cutting tools, punches, gauges |
Which should you choose? P20 (1.2311) is the economical standard for most moulds. Choose 1.2738 when the block is very thick and uniform hardness through the core matters. OHNS is a cold-work tool steel for cutting and blanking tools, not a pre-hardened mould steel.
Heat Treatment of P20 Tool Steel
- Supplied condition: pre-hardened and tempered – no heat treatment is needed before use.
- Stress relieving: after heavy rough machining, heat to about 480 °C (below the original tempering temperature), hold 1 hour per 25 mm of thickness and cool slowly.
- Re-hardening (if required): austenitise at about 840–870 °C, quench in oil or gas, then temper immediately to the required hardness.
- Nitriding: P20 can be gas or plasma nitrided to give a hard, wear-resistant surface on a tough core.
- Carburising: can be case-hardened for applications needing a very hard surface.
Applications of P20 Tool Steel
- Plastic injection moulds and mould cavities
- Blow moulds and extrusion dies for plastics
- Mould bases, bolsters and holder blocks
- Die-casting dies for low-melting alloys such as zinc
- Automotive plastic component and household appliance moulds
- Press brake dies, jigs, fixtures and engineering tooling
AISI P20 tool steel round bar is preferred for medium-to-large moulds where toughness, machinability and polish matter more than very high hardness.
Related tool and Alloy Steel Bars:
Why Buy P20 Tool Steel Round Bar from ASC LLP?
- Certified material from established mills, with EN 10204 3.1 test certificates.
- Ready stock of P20 round, square and flat bars, plus 1.2311 forgings.
- Cut-to-size service – saw-cut pieces to reduce waste and machining time.
- Inspection before dispatch – hardness checks and ultrasonic testing.
- Technical guidance on choosing between P20, 1.2738 and other tool steels.
Frequently Asked Questions – P20 Tool Steel
What is P20 tool steel used for?
P20 is used mainly for plastic injection moulds, blow moulds, mould bases and holder blocks, and for die-casting dies for low-melting alloys such as zinc. It is also used for jigs, fixtures and general engineering tooling.
What is the hardness of P20 steel?
P20 is normally supplied pre-hardened to about 28–34 HRC (approximately 280–320 HB). Its surface can be raised further by nitriding.
What is the equivalent of P20 tool steel?
P20 is equivalent to DIN 1.2311 / 40CrMnMo7, UNS T51620 and China GB 3Cr2Mo, and is covered by ASTM A681. The nickel-bearing variant is 1.2738.
What is the difference between P20 and 1.2738?
1.2738 is P20 with about 1% nickel added. The nickel gives more uniform hardness and better toughness in very large, thick blocks, so 1.2738 is preferred for big moulds while P20 (1.2311) suits small to medium moulds at lower cost.
Does P20 need heat treatment after machining?
No. P20 is supplied pre-hardened, so moulds can be used after machining. A stress relief at about 480 °C is recommended after heavy rough machining to reduce distortion.
Can P20 tool steel be welded?
Yes. P20 can be weld-repaired using a matching filler, with preheating and post-weld stress relief to avoid cracking.
Global Reach
ASC LLP has a robust global presence, committed to delivering unparalleled service and quality to clients around the world. Our dedication to prompt delivery and exceptional customer care sets us apart in the industry. Major corporations across the USA, Europe, Asia, and other regions place their trust in our high-quality P20 tool steel round bars. This widespread trust underscores our reputation for reliability and excellence. By consistently meeting and exceeding the expectations of our international clientele, we continue to solidify our position as a leader in the global steel market.
Countries We Export To
UNITED STATES, EUROPE, UK, UAE, SAUDI ARABIA, OMAN, KUWAIT, JORDAN, QATAR, INDONESIA, MALAYSIA, BRAZIL, SPAIN, ITALY, FRANCE, GERMANY, BAHRAIN, SRI LANKA, AZERBAIJAN, AUSTRALIA, AUSTRIA, PHILIPPINES, TURKEY, RUSSIA, IRAN, IRAQ, CANADA, KOREA, JAPAN, YEMEN, FINLAND, ZIMBABWE, HUNGARY, PORTUGAL, VIETNAM, MOROCCO, THAILAND, SOUTH AFRICA, MEXICO, SINGAPORE, GREECE, KUWAIT, POLAND, NEW ZEALAND, SWEDEN, SWITZERLAND, BELGIUM, BHUTAN, BANGLADESH, TAIWAN, ROMANIA, CAMBODIA, KAZAKHSTAN, AFGHANISTAN.
