Steel NAK80 · heat-treated state
Steel NAK80 Q&T
Properties of the Q&T condition, compared with the other NAK80 tempers.
Re-heat-treatment route after weld repair or after machining in the soft state; restores full pre-hard properties.
What is NAK80 Q&T?
NAK80 Q&T is NAK80 heat treated to Q&T — re-heat-treatment route after weld repair or after machining in the soft state; restores full pre-hard properties. NAK80 Q&T has a yield strength of 1,180 MPa (171 ksi) and a tensile strength of 1,330 MPa (193 ksi) — stronger than 94% of steel grades. Elongation at break is 11% and the elastic modulus is 205 GPa (29.7 Msi). NAK80 Q&T 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; Q&T is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 95/100, better than 100% of steel grades
- High strength — 1,180 MPa (171 ksi), better than 94% of steel grades
Limitations
- Limited ductility — 11%, worse than 89% of steel grades
- High embodied carbon — 2.6 kg CO₂/kg, worse than 86% 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 79% of steel grades
NAK80 Q&T properties
Typical room-temperature values for NAK80 Q&T — 9 properties are specific to this condition; the rest are grade-level values shared by every NAK80 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical2
NAK80 Q&T 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 Q&T has a yield strength of 1,180 MPa (171 ksi) and a tensile strength of 1,330 MPa (193 ksi) — stronger than 94% of steel grades. Elongation at break is 11% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
NAK80 Q&T 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 Q&T 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 Q&T takes about 36 MJ of energy and emits 2.6 kg of CO₂ — more than 88% of steel grades. Typical recycled content is 30%.
Manufacturability7
NAK80 Q&T's machinability is fair (52/100, better than 52% of steel grades); weldability fair (50/100); formability poor (30/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other NAK80 tempers and conditions
NAK80 is also supplied in 3 other conditions. The full side-by-side table is on the NAK80 overview.
- AnnealedDefaultRarely stocked; used when very heavy roughing or cold work is needed before re-solution-treating and aging back to 40 HRC.700 MPa yield · 28 HRC
- Q&TRe-heat-treatment route after weld repair or after machining in the soft state; restores full pre-hard properties.1,180 MPa yield · 41 HRC
- PrehardStandard stock condition: machine straight to finished cavity, no heat treatment and no distortion risk.1,150 MPa yield · 40 HRC
Working with NAK80 Q&T
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.
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.
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 | — |
NAK80 Q&T — frequently asked
What is NAK80 Q&T used for?
NAK80 Q&T 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 Q&T?
NAK80 Q&T has a typical yield strength of 1,180 MPa (171 ksi) and a tensile strength of 1,330 MPa (193 ksi) — stronger than 94% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is NAK80 Q&T easy to machine?
Reasonably — machinability is rated fair (52/100, better than 52% 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 Q&T 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 Q&T?
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 Q&T 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 Q&T?
NAK80 Q&T 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.
Can FabDigit make parts in NAK80 Q&T?
Yes — NAK80 Q&T is available for CNC machining with instant online pricing. 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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.