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P20 1.2311 plastic mold steel

1.2311 plastic mold steel offers excellent machinability, uniform hardness, and good polishability. With pre-hardened delivery condition and stable performance, ideal for general plastic molds, mold bases, and low-load forming tools.

Standard: AISI P20, DIN 1.2311, JIS SCM440 MOD, GB 3Cr2Mo
Technique: EAF + LF + VD, forged, multi-directional forging ratio ≥4, quenched and tempered
Shape: Round, Flat, Plates, Blocks
Heat treatment: Supplied in pre-hardened condition, hardness 28–32 HRC (quenched and tempered). Annealed supply available on request
Surface Treatment: Turned, milled / ground, sawn ends. Black (hot-rolled / forged surface) available for large sections
Tolerance: flat bars & plates thickness: +0.5/-0.0 mm (turned); forged blocks: ±0.2 mm
MOQ: 1 Ton

We supply DIN 1.2311 in various custom sizes

Chemical Composition (%)

Grade	C	Si	Mn	P (≤)	S (≤)	Cr	Mo	Ni
1.2311 (40CrMnMo7)	0.35–0.45	0.20–0.40	1.30–1.60	0.035	0.035	1.80–2.10	0.15–0.25	≤0.40
P20	0.28–0.40	0.20–0.80	0.60–1.00	0.030	0.030	1.40–2.00	0.30–0.55	0.30–0.55
3Cr2Mo	0.28–0.40	0.20–0.80	0.60–1.00	0.030	0.030	1.40–2.00	0.30–0.55	0.25–0.55
SCM440 MOD	0.35–0.43	0.20–0.50	0.80–1.20	≤0.020	≤0.005	1.40–1.80	0.25–0.45	0.30–0.55

Main characteristics of 1.2311 tool steel

P20 | 1.2311 tool steel applications

1.2311 steel for Industrial Parts & Extrusion Tools

Pre-hardened 1.2311 delivers uniform hardness and good toughness, enabling reliable performance in structural components and light-duty extrusion tools without further treatment.

1.2311 steel for Die-Casting & Stamping Tools

Balanced strength and wear resistance allow 1.2311 to withstand moderate thermal and mechanical loads in selected die-casting inserts and stamping applications.

1.2311 steel for Plastic Mould & Mould Base

Excellent polishability and consistent hardness make 1.2311 the industry standard for plastic injection moulds and mould bases requiring good machinability and long service life.

Our Production Technology For 1.2311 (40CrMnMo7 / AISI P20 / 3Cr2Mo) Prehardened Plastic Mold Steel

Ultrasonic testing (UT) 100% as per EN 10228-3 Class 4 or SEP 1921 Class E/e
Micro Cleanliness per DIN 50602 K4 ≤ 20 or ASTM E45 Method A (thin: A≤1.5, B/C/D≤2)
Polishability good, suitable for A-2 surface finish and texturing
Nitridability surface hardness 700–850 HV after nitriding
Delivery condition: Quenched and tempered (prehardened), hardness 280 – 325 HB (28 – 34 HRC)

mechanical properties & heat treatment of 1.2311 steel

Heat temperature	Start forging temperature	Finish forging temperature	Cooling method
1050 °C	1050 – 1000 °C	≥ 930 °C	Pit, sand, or furnace cooling

Annealing

Heat slowly and uniformly to 710 – 740°C (or 770–790°C when annealing after forging)
Hold at temperature for sufficient time to ensure uniform temperature throughout the section (minimum 2 minutes per mm of thickness)
Cool slowly in the furnace at a controlled rate to room temperature
Hardness after annealing: ≤ 230 – 250 HB
Annealing in a protective atmosphere is recommended to reduce decarburization and surface scaling

Hardening

1.2311 (40CrMnMo7 / P20) is a prehardened plastic mold steel. It is typically supplied in the quenched and tempered condition with hardness 280–325 HB (28–34 HRC) and does not require further heat treatment for most applications. However, when rehardening is required for specific applications (e.g., extending mold life beyond 800,000 cycles), the following parameters apply
Pre-heating (recommended): Preheat to 500 – 650°C and hold for 2–4 hours to ensure uniform temperature distribution
Austenitizing temperature: 840 – 880°C.
Preferred range: 840 – 870°C
Holding time: After temperature equalization, hold for 1 minute per mm of section thickness (minimum 2 hours for larger sections)
Quenching media:
Oil (preferred for most sections) — quench immediately after holding
Polymer — also suitable
Air (still air) — for minimizing distortion, suitable for smaller sections and less critical applications
Warm bath at 180–220°C — as an alternative hardening procedure for complex shapes
Hardness after quenching: approx. 51 HRC (approx. 500 HB)

Stress relieving

Perform after rough machining or heavy stock removal, especially for tools with complex shapes or unbalanced cross-sections, to reduce the risk of distortion during final heat treatment
Heat carefully to 560 – 650°C (recommended: max. 30°C below the tempering temperature used for the prehardened condition)
Hold at temperature for 1 – 2 hours (minimum 2 minutes per mm of thickness)
Air cool or furnace cool after holding
This operation is recommended to eliminate residual stresses induced by mechanical working

Tempering

Temper immediately after the workpiece cools to handwarm temperature (approx. 50–70°C). Delayed tempering may cause cracking
Number of tempers: Minimum 2 times. Double tempering is recommended to improve toughness and ensure complete transformation of retained austenite. The second tempering must be performed at a temperature max. 30°C below the first tempering temperature
Holding time: Soak for at least 3 minutes per mm of section thickness (minimum 2 hours per cycle)
Cooling method: Air cool after each tempering cycle (must cool to room temperature before the next tempering)
Tempering temperature selection:
550 – 620°C — Standard tempering range after hardening from 860–880°C
180 – 220°C (lowtemperature tempering) — For applications requiring maximum hardness after rehardening (approx. 48–51 HRC) while preventing cracking

Why Choose NSPM as Your 1.2311 Tool Steel Supplier

Source Direct

Direct mill cooperation ensures stable supply, competitive pricing, and consistent quality. Global resource integration and strong supply chain management guarantee reliable material sourcing and long-term availability.

Stock Ready

50,000+ tons inventory across 11 warehouses enables fast delivery. Flexible cutting, short lead times, and ready stock support urgent demands and improve customers’ production efficiency.

Expert Team

600+ professionals, including R&D specialists and technical engineers, provide application-driven support. Fast response and deep tooling knowledge ensure accurate solutions for diverse industrial needs.

Fully Inspected

Strict quality control system with full traceability, UT testing, and heat treatment records. Certified standards (ISO, CE) ensure every material meets high-performance and reliability requirements.

Full-Chain Machining

From steel supply to precision machining, heat treatment, and equipment manufacturing, NSPM offers integrated solutions that enhance accuracy, efficiency, and overall tooling performance.