P21 Mod NAK80 plastic mold steel
NAK80 tool steel is a pre-hardened grade with exceptional polishability, superior surface gloss and excellent dimensional stability. It is ideal for automotive lamp, high-gloss home appliance and precision optical housing molds.
- Standard: AISI P21 Mod, JIS NAK80, GB 10Ni3MnCuAl
- Technique: EAF + LF + VD or ESR, forged, multi-directional forging ratio ≥4, quenched and tempered (pre-hardened)
- Shape: Round, Flat, Plates, Blocks
- Heat treatment: Supplied in pre-hardened condition, hardness 38–42 HRC (quenched and tempered)
- 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 JIS NAK80 in various custom sizes
plate
flat size range
- Thickness: 10-120 mm
- Width: 40-810 mm
block size range
- Thickness: 200-400 mm
- Width: 300-1200 mm
round size range
- Diameter: φ10-400 mm
Chemical Composition (%)
Grade | C | Si | Mn | Cr | Ni | Cu | Al | 其他 |
NAK80 | 0.15–0.25 | 0.15–0.35 | 0.30–0.50 | 1.80–2.20 | — | 0.80–1.20 | 0.80–1.20 | 0.20≤Mo≤0.40 |
10Ni3MnCuAl | ≤0.12 | 0.20–0.50 | 1.00–2.00 | ≤0.30 | 2.80–3.40 | 0.80–1.20 | 0.80–1.20 | Mo≤0.20 |
P21 MOD | 0.06–0.12 | 0.20–0.50 | 1.00–1.50 | ≤0.50 | 3.00–3.80 | 0.90–1.20 | 0.90–1.20 | P≤0.020, S≤0.005 |
Main characteristics of NAK80 tool steel
- Superior polishability - achieves high-gloss mirror surface finish
- Pre-hardened condition - no extra heat treatment needed
- Excellent dimensional stability - maintains tight precision tolerances
- Good machinability - cuts machining time and tooling cost
P21 Mod | NAK80 tool steel applications
NAK80 steel for Automotive Lamp Mold
NAK80’s superior polishability and pre-hardened high hardness deliver flawless mirror finishes, ensuring precision and long tool life in high-volume automotive lamp production.
NAK80 steel for High-Gloss Home Appliance Mold
The easy-to-machine nature of NAK80 enables fast, cost-effective production of high-gloss, scratch-resistant panels for premium home appliances without additional heat treatment.
NAK80 steel for Precision Optical Housing Mold
Excellent dimensional stability and uniform hardness make NAK80 ideal for complex molds requiring tight tolerances and mirror finishes, such as camera and lens housings.
Our Production Technology For NAK80 (AISI P21 Mod / 10Ni3MnCuAl) Prehardened Mirror-Finish Plastic Mold Steel
- ESR / DAIDO Special Melting Technology (Vacuum Degassing + ESR)
- Forged or Hot Rolled
- Solution Treatment (Quenched)
- Precipitation Hardening (Aged / Tempered) — Prehardened Delivery Condition
- Machined surface / Peeled / Ground / Polished
- Ultrasonic testing (UT) 100% as per EN 10228-3, SEP 1921, or ASTM A388 (upon request)
- Micro Cleanliness as per ASTM E45 — exceptionally high purity level due to special melting process
- Delivery condition: Prehardened (Precipitation-hardened), hardness 37 – 43 HRC (factory supply, ready for direct use)
- Alternative delivery: Solution-treated condition (soft), hardness 29 – 32 HRC (supplied for easier cutting and subsequent age-hardening after mold finishing)
mechanical properties & heat treatment of NAK80 steel
| Heat temperature | Start forging temperature | Finish forging temperature | Cooling method |
| 860 – 920 °C | 860 – 900 °C | ≥ 850 °C | Pit, sand, or furnace cooling |
Annealing
- Heat slowly and uniformly to 800 – 840°C
- Hold at temperature for 1 – 2 hours (depending on section thickness)
- Cool slowly in the furnace (furnace cooling) to room temperature
- Hardness after annealing: Reduced (enhanced toughness), no specific value provided
- Annealing in a protective atmosphere is recommended to reduce decarburization and surface scaling
Hardening
- For prehardened delivery condition: The steel is supplied at 37–43 HRC and does not require additional age hardening for most applications. For applications requiring rehardening after welding or after machining of solution-treated material, age hardening is performed as follows
- Number of treatments: Minimum 1 treatment (for restoration of hardness after welding or after solution treatment). For critical applications requiring optimum property stability, double aging is recommended
- Holding time: Soak for 2 – 6 hours (depending on section thickness). Daido specifications: 5–6 hours at 500°C for optimum precipitation hardening
- Cooling method: Air cool after aging
Stress relieving
- For prehardened material (37–43 HRC), stress relieving is generally not required due to the inherent stability of the precipitation-hardened microstructure
- Perform after rough machining, heavy stock removal, EDM, or welding for tools with complex shapes or unbalanced crosssections, to reduce the risk of distortion during final finishing
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Temperature: 20 – 30°C below the last aging (tempering) temperature.
Recommended range: 450 – 500°C.
Alternative range: 500 – 550°C for general stress relief.
Meusburger recommendation: 550°C before nitriding - Holding time: 1 – 2 hours (minimum 2 minutes per mm of section thickness)
- Cooling method: Slow cool in the furnace, or air cool after holding
- This operation is recommended to eliminate residual stresses induced by mechanical working, EDM, or welding, and to reduce distortion during further processing or service
Tempering
- NAK80 is a precipitation-hardening (aging) steel. It is normally supplied in the prehardened condition and does not require solution treatment. However, when the steel is delivered in the solution-treated (soft) condition (29–32 HRC), or when the steel has been annealed or forged and requires restoration to the prehardened condition, the following solution treatment parameters apply
- Pre-heating (recommended): Preheat to 600°C gradually to reduce thermal shock before austenitizing
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Solution treatment (austenitizing) temperature: 840 – 900°C.
Meusburger range: 840 – 870°C.
Alternative range: 830 – 860°C - Holding time: After temperature equalization, hold for at least 2 hours (or 30–60 minutes per 25mm of section thickness)
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Quenching media:
Air (still air or pressurized gas) — preferred for minimizing distortion.
Oil or polymer — for faster cooling, particularly for larger sections.
For integrated forging + solution treatment process: After hot forging, the steel is directly placed into a quenching medium (oil or polymer) and cooled to 150 – 250°C to obtain a bainitic structure - Hardness after solution treatment: 29 – 32 HRC (soft condition)
Why Choose NSPM as Your NAK80 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.
