Steel D1-NIT
Finish state
AISI/SAE D1 · UNS T30401
NIT = hardened, tempered and gas/plasma nitrided surface
Adds a very hard, galling-resistant case for forming stainless or coated sheet; core stays at temper hardness.
Values for the NIT condition
Other D1 tempers and conditions
D1 is listed in 6 conditions; see the grade overview at D1.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ADefault Solution annealed | Standard mill-supplied condition for machining the die before hardening. | 420 | 760 | 16 | 235 HB | — |
Hardened & high-temperature tempered ~500–540 °C, 52–56 HRC | Choose when tools run warm or need extra toughness/dimensional stability, or before nitriding. | 1,500 | 1,750 | 3 | 54 HRC | — |
Hardened & tempered ~200–260 °C, 57–59 HRC | Best general-purpose balance of wear resistance and chipping resistance for cold-work dies. | 1,600 | 1,900 | 2 | 58 HRC | — |
Hardened & tempered ~150–200 °C, 60–62 HRC | Maximum wear resistance for blanking/trimming dies on thin, non-abusive work. | 1,700 | 2,000 | 1 | 61 HRC | — |
NITThis page Hardened, tempered and gas/plasma nitrided surface | Adds a very hard, galling-resistant case for forming stainless or coated sheet; core stays at temper hardness. | 1,700 | 1,950 | 1 | 58 HRC | 2.6 % IACS |
Hardened + deep-freeze (cryogenic) + double temper, 61–63 HRC | Use where residual austenite must be eliminated for size stability (gauges, precision punches). | 1,850 | 2,100 | 0.5 | 62 HRC | 2.6 % IACS |
What is D1-NIT?
D1-NIT is D1 supplied in the NIT condition — adds a very hard, galling-resistant case for forming stainless or coated sheet; core stays at temper hardness. D1-NIT has a yield strength of 1,700 MPa (247 ksi) and a tensile strength of 1,950 MPa (283 ksi) — stronger than 99% of steel grades. Elongation at break is 1% and the elastic modulus is 210 GPa (30.5 Msi). D1-NIT has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 95% of steel grades. It melts at 1,421°C (2,590 °F). A is the default condition FabDigit quotes; NIT is available on request or by drawing note.
Advantages
- High strength — 1,700 MPa (247 ksi), better than 99% of steel grades
- Good corrosion resistance — 35/100, better than 97% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
- High service temperature — 450°C (842 °F), better than 86% of steel grades
Limitations
- Difficult to machine — 3/100, worse than 100% of steel grades
- Difficult to weld — 3/100, worse than 100% of steel grades
- Limited formability — 1/100, worse than 100% of steel grades
- Limited ductility — 1%, worse than 99% of steel grades
- Low fracture toughness — 18 MPa·√m (16.4 ksi·√in), worse than 99% of steel grades
D1-NIT properties
Typical room-temperature values for D1-NIT; 21 are specific to this condition. Other listed values are D1 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
D1-NIT has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 95% of steel grades. It melts at 1,421°C (2,590 °F).
Mechanical16
D1-NIT has a yield strength of 1,700 MPa (247 ksi) and a tensile strength of 1,950 MPa (283 ksi) — stronger than 99% of steel grades. Elongation at break is 1% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
D1-NIT is rated for continuous service to 450°C (842 °F). It conducts heat at 19 W/m·K (11 BTU/hr·ft·°F), worse than 97% of steel grades. Thermal expansion is 10.4 µm/m·K (5.78 µin/in·°F).
Electrical3
D1-NIT conducts electricity at 2.6 % IACS, worse than 97% of steel grades.
Chemical & Environmental3
Corrosion resistance is fair (35/100), better than 97% of steel grades.
Sustainability4
Producing a kilogram of D1-NIT takes about 35 MJ of energy and emits 2.6 kg of CO₂ — more than 87% of steel grades. Typical recycled content is 35%.
Manufacturability7
D1-NIT's machinability is not recommended (3/100, worse than 100% of steel grades); weldability not recommended (3/100); formability not recommended (1/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with D1-NIT
Is D1 easy to machine?
Machine only in the annealed state with rigid setups, sharp carbide or coated tooling and modest speeds; after hardening it is a grinding/EDM-only material (leave 0.2–0.4 mm grind stock).
Can D1 be welded?
Not a structural weld alloy — repair-weld only with matching high-Cr filler, preheat 400–500 °C, keep interpass temperature, then re-temper immediately to avoid quench cracks.
Can D1 be formed, bent or molded?
Hot work 900–1050 °C with slow furnace cooling; anneal 850–870 °C then harden 980–1010 °C, air or plate quench, double temper 150–200 °C (or 500–540 °C for secondary hardening) with size change under ~0.05 %.
What surface finishes work on D1?
Takes a good mirror polish at 58–62 HRC; protect with oil, black oxide, hard chrome, nitriding or PVD TiN/CrN — the 12 % Cr is not enough to prevent rust in storage.
D1 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 |
|---|---|---|
| Clower than D2 (1.4–1.6 %) | 0.85 – 1.1 | 1 |
| Cr | 11 – 13 | 12 |
| Mo | 0.7 – 1.2 | 1 |
| Voptional, max limit | ≤ 1.1 | 0.3 |
| Mn | ≤ 0.6 | 0.35 |
| Si | ≤ 0.6 | 0.3 |
| Niresidual | ≤ 0.3 | — |
| Curesidual | ≤ 0.25 | — |
| Wresidual/optional | ≤ 0.5 | — |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Fe | balance | — |
D1-NIT — frequently asked
What is D1-NIT used for?
D1-NIT is typically used for blanking dies, forming dies and thread rolling dies. In short: D2-class wear resistance; air-hardening long-run die steel; grind-only when hardened.
What is the yield strength of D1-NIT?
D1-NIT has a typical yield strength of 1,700 MPa (247 ksi) and a tensile strength of 1,950 MPa (283 ksi) — stronger than 99% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is D1-NIT easy to machine?
Not especially — machinability is rated not recommended (3/100, worse than 100% of steel grades). Machine only in the annealed state with rigid setups, sharp carbide or coated tooling and modest speeds; after hardening it is a grinding/EDM-only material (leave 0.2–0.4 mm grind stock).
Can D1-NIT be welded?
Not readily — weldability is rated not recommended (3/100). Not a structural weld alloy — repair-weld only with matching high-Cr filler, preheat 400–500 °C, keep interpass temperature, then re-temper immediately to avoid quench cracks.
What surface finishes work on D1-NIT?
Takes a good mirror polish at 58–62 HRC; protect with oil, black oxide, hard chrome, nitriding or PVD TiN/CrN — the 12 % Cr is not enough to prevent rust in storage.
Can D1-NIT be formed, bent or molded?
Hot work 900–1050 °C with slow furnace cooling; anneal 850–870 °C then harden 980–1010 °C, air or plate quench, double temper 150–200 °C (or 500–540 °C for secondary hardening) with size change under ~0.05 %.
What is the maximum service temperature of D1-NIT?
D1-NIT is rated for continuous use to about 450°C (842 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between D1-A and D1 QT-CRYO?
A is the default condition — standard mill-supplied condition for machining the die before hardening. QT-CRYO: use where residual austenite must be eliminated for size stability (gauges, precision punches). Yield strength is 420 MPa in A versus 1,850 MPa in QT-CRYO.
Sources
- ASTM A681 Standard Specification for Tool Steels Alloy — ASTM International (2022)
- SAE J437/J438 Tool and Die Steels — SAE International (2007)
- ASM Handbook Vol. 1: Properties and Selection — Irons, Steels, and High-Performance Alloys (Tool Steels) — ASM International (1990)
- Tool Steels, 5th ed. (Roberts, Krauss, Kennedy) — ASM International (1998)
- GB/T 1299 (Cr12MoV / Cr12Mo1V1) — SAC / (2014)
- Cold-work tool steel D2/1.2379 datasheets (Böhler K110, Uddeholm Sverker 21) — voestalpine / Uddeholm (2022)
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.