Steel NAK80
NAK80 is a Ni-Al-Cu precipitation-hardening prehardened plastic mould steel supplied at about 40 HRC (37–43 HRC), ready to finish-machine with no further heat treatment and no distortion allowance.
Values for the Annealed condition
NAK80 tempers and conditions
NAK80 is supplied in 4 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault softened for heavy machining (approx. 25–30 HRC) | Rarely stocked; used when very heavy roughing or cold work is needed before re-solution-treating and aging back to 40 HRC. | 700 | 900 | 18 | 28 HRC | — |
Pre-hardened | Standard stock condition: machine straight to finished cavity, no heat treatment and no distortion risk. | 1,150 | 1,300 | 12 | 40 HRC | — |
pre-hard core with gas/plasma nitrided case (~900–1000 HV surface) | Pick when abrasive glass/mineral-filled resins demand a wear-resistant cavity surface while keeping the 40 HRC tough core. | 1,150 | 1,300 | 10 | 40 HRC | 5.7 % IACS |
Quenched and tempered | Re-heat-treatment route after weld repair or after machining in the soft state; restores full pre-hard properties. | 1,180 | 1,330 | 11 | 41 HRC | 5.7 % IACS |
What is NAK80?
NAK80 is a Ni-Al-Cu precipitation-hardening prehardened plastic mould steel supplied at about 40 HRC (37–43 HRC), ready to finish-machine with no further heat treatment and no distortion allowance. Its clean, fine, non-resulfurized structure (unlike free-machining NAK55) takes a mirror polish and responds well to EDM, texture etching and weld repair, suiting high-gloss transparent parts, optical components and precision injection moulds. Corrosion resistance is only marginally better than plain low-alloy steel, so plating or rust prevention is needed, service must stay below the roughly 500 °C ageing temperature, and machining at 40 HRC costs more than P20. NAK80 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). NAK80 has a yield strength of 700 MPa (102 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 81% of steel grades. Elongation at break is 18% and the elastic modulus is 205 GPa (29.7 Msi).
What is NAK80 used for?
- Injection moulds for high-gloss transparent parts
- Optical lens moulds
- Precision cavity and core inserts
- Cosmetic and consumer housing moulds
- Photo-etched and textured cavity plates
- Medical device moulds
- Mould slides and inserts
Advantages
- Easy to machine — 70/100, better than 96% of steel grades
- Polishes to a fine finish — 75/100, better than 94% of steel grades
- High strength — 700 MPa (102 ksi), better than 81% of steel grades
Limitations
- High embodied carbon — 2.6 kg CO₂/kg, worse than 87% of steel grades
- Poor heat conductor — 30 W/m·K (17.3 BTU/hr·ft·°F), worse than 83% of steel grades
- Low electrical conductivity — 5.7 % IACS, worse than 80% of steel grades
- Low fracture toughness — 60 MPa·√m (54.6 ksi·√in), worse than 78% of steel grades
NAK80 properties
Typical room-temperature values for NAK80-Annealed; bars are the position among steel grades.
Physical2
NAK80 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).
Mechanical16
NAK80 has a yield strength of 700 MPa (102 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 81% of steel grades. Elongation at break is 18% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
NAK80 is rated for continuous service to 400°C (752 °F). It conducts heat at 30 W/m·K (17.3 BTU/hr·ft·°F), worse than 83% of steel grades. Thermal expansion is 12.5 µm/m·K (6.94 µin/in·°F).
Electrical3
NAK80 conducts electricity at 5.7 % IACS, worse than 80% of steel grades.
Chemical & Environmental2
Corrosion resistance is poor (20/100), better than 87% of steel grades.
Sustainability4
Producing a kilogram of NAK80 takes about 36 MJ of energy and emits 2.6 kg of CO₂ — more than 89% of steel grades. Typical recycled content is 30%.
Manufacturability7
NAK80's machinability is very good (70/100, better than 96% of steel grades); weldability fair (50/100); formability poor (30/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. NAK80 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with NAK80
Is NAK80 easy to machine?
Machine directly at 40 HRC with coated carbide (or CBN for finishing); rigid setups, 60–120 m/min, light radial engagement — EDM and engraving behave well and no post-heat-treat distortion allowance is needed.
Can NAK80 be welded?
Repairable by TIG or laser with matching NAK80/maraging-type filler; preheat 250–350 °C, low heat input, then re-age ~500 °C ×3–5 h to recover cavity hardness and colour match.
Can NAK80 be formed, bent or molded?
Supplied in the hardened condition, so no cold forming — shape by milling, EDM, grinding; hot working (1100→900 °C forge) only at the mill followed by solution + aging.
Manufacturability
The process limits FabDigit applies to NAK80. Every NAK80 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Better70 / 100 |
|---|---|
| ISO material group | P.2 |
| Cutting speed (rough / finish) | 180 / 210 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 5× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
NAK80 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 |
|---|---|---|
| C | 0.1 – 0.2 | 0.15 |
| Si | 0.1 – 0.5 | 0.3 |
| Mn | 1.2 – 1.8 | 1.5 |
| Niwith Al and Cu forms the precipitation-hardening system | 2.5 – 3.5 | 3 |
| Cu | 0.8 – 1.2 | 1 |
| AlNi-Al intermetallic aging response | 0.8 – 1.2 | 1 |
| Mo | 0.15 – 0.4 | 0.3 |
| Skept low (non-free-cutting) for mirror polishability, unlike NAK55 | ≤ 0.01 | 0.01 |
| P | ≤ 0.03 | 0.02 |
| Fe | balance |
What surface finishes work on NAK80?
Excellent mirror polishability (Ra <0.01 µm achievable, #10000 attainable) thanks to low sulfur and fine uniform structure; accepts texturing/etching, hard chrome or electroless nickel for corrosive resins, and nitriding or PVD for wear.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Plating
CVD Coating
Black / Phosphate
Thermal Spray
How much does NAK80 cost?
NAK80 is a standard-cost steel ($$), cheaper than about 59% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
NAK80 — frequently asked
What is NAK80 used for?
NAK80 is typically used for injection moulds for high-gloss transparent parts, optical lens moulds, precision cavity and core inserts, cosmetic and consumer housing moulds, photo-etched and textured cavity plates and medical device moulds. In short: premium mirror-polish mold.
What is the yield strength of NAK80?
NAK80 has a typical yield strength of 700 MPa (102 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 81% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is NAK80 easy to machine?
Yes — machinability is rated very good (70/100, better than 96% of steel grades). Machine directly at 40 HRC with coated carbide (or CBN for finishing); rigid setups, 60–120 m/min, light radial engagement — EDM and engraving behave well and no post-heat-treat distortion allowance is needed.
Can NAK80 be welded?
With care — weldability is rated fair (50/100). Repairable by TIG or laser with matching NAK80/maraging-type filler; preheat 250–350 °C, low heat input, then re-age ~500 °C ×3–5 h to recover cavity hardness and colour match.
What surface finishes work on NAK80?
Excellent mirror polishability (Ra <0.01 µm achievable, #10000 attainable) thanks to low sulfur and fine uniform structure; accepts texturing/etching, hard chrome or electroless nickel for corrosive resins, and nitriding or PVD for wear.
Can NAK80 be formed, bent or molded?
Supplied in the hardened condition, so no cold forming — shape by milling, EDM, grinding; hot working (1100→900 °C forge) only at the mill followed by solution + aging.
What is the maximum service temperature of NAK80?
NAK80 is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between NAK80 Annealed and NAK80 Prehard?
Annealed is the default condition — rarely stocked; used when very heavy roughing or cold work is needed before re-solution-treating and aging back to 40 HRC. Prehard: standard stock condition: machine straight to finished cavity, no heat treatment and no distortion risk. Yield strength is 700 MPa in Annealed versus 1,150 MPa in Prehard.
How much does NAK80 cost?
NAK80 is a standard-cost steel ($$), cheaper than about 59% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in NAK80?
Yes — NAK80 is available for CNC machining; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- NAK80 Pre-hardened Mirror-finish Plastic Mold Steel — Daido Steel (2020)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels and High-Performance Alloys — ASM International (1990)
- Tool Steels, 5th ed. — ASM International (1998)
- Mold steel comparison tables (NAK80 / P20 / 718H) — Ensinger–Hasco style tooling data compilations (2022)
- (NAK80/718H/P20) (2025)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.