Steel A3 Nitrided
Finish state
AISI/SAE A3 · UNS T30103
Use when galling or adhesive wear dominates; core stays at 58–60 HRC with ~1100 HV case.
Values for the Nitrided condition
Other A3 tempers and conditions
A3 is listed in 6 conditions; see the grade overview at A3.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Stress relieved after rough machining (~650–700 °C, annealed base) | Intermediate step on large or asymmetric tools to minimise distortion during air hardening. | 420 | 740 | 21 | 18 HRC | 2.7 % IACS |
AnnealedDefault soft, as-supplied bar / plate / precision ground flat stock | Standard stock condition for machining the tool before hardening. | 430 | 760 | 20 | 19 HRC | — |
Hardened and tempered to 56–58 HRC | Pick when impact and chipping resistance matter more than maximum wear life. | 1,700 | 1,950 | 3 | 57 HRC | — |
NitridedThis page Hardened, tempered and gas/plasma nitrided surface | Use when galling or adhesive wear dominates; core stays at 58–60 HRC with ~1100 HV case. | 1,750 | 2,000 | 1.5 | 59 HRC | 2.7 % IACS |
Hardened and tempered to 58–60 HRC | General-purpose working hardness for blanking and forming dies — balanced wear and toughness. | 1,850 | 2,100 | 2 | 59 HRC | — |
Hardened and tempered to 60–62 HRC | Highest practical wear resistance for A3 — for abrasive blanking, trim edges and gauges with rigid support. | 2,000 | 2,250 | 1 | 61 HRC | — |
What is A3 Nitrided?
A3 Nitrided is A3 supplied in the Nitrided condition — use when galling or adhesive wear dominates; core stays at 58–60 HRC with ~1100 HV case. A3 Nitrided has a yield strength of 1,750 MPa (254 ksi) and a tensile strength of 2,000 MPa (290 ksi) — stronger than 99% of steel grades. Elongation at break is 1.5% and the elastic modulus is 203 GPa (29.4 Msi). A3 Nitrided has a density of 7.86 g/cm³ (0.284 lb/in³), heavier than 90% of steel grades. It melts at 1,420°C (2,588 °F). Annealed is the default condition FabDigit quotes; Nitrided is available on request or by drawing note.
Advantages
- High strength — 1,750 MPa (254 ksi), better than 99% of steel grades
- Good corrosion resistance — 25/100, better than 92% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
Limitations
- Difficult to machine — 5/100, worse than 100% of steel grades
- Difficult to weld — 3/100, worse than 100% of steel grades
- Limited formability — 2/100, worse than 100% of steel grades
- Limited ductility — 1.5%, worse than 99% of steel grades
- Low electrical conductivity — 2.7 % IACS, worse than 96% of steel grades
A3 Nitrided properties
Typical room-temperature values for A3 Nitrided; 21 are specific to this condition. Other listed values are A3 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
A3 Nitrided has a density of 7.86 g/cm³ (0.284 lb/in³), heavier than 90% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical15
A3 Nitrided has a yield strength of 1,750 MPa (254 ksi) and a tensile strength of 2,000 MPa (290 ksi) — stronger than 99% of steel grades. Elongation at break is 1.5% and the elastic modulus is 203 GPa (29.4 Msi).
Thermal6
A3 Nitrided is rated for continuous service to 400°C (752 °F). It conducts heat at 24 W/m·K (13.9 BTU/hr·ft·°F), worse than 90% of steel grades. Thermal expansion is 10.7 µm/m·K (5.94 µin/in·°F).
Electrical3
A3 Nitrided conducts electricity at 2.7 % IACS, worse than 96% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (25/100), better than 92% of steel grades.
Sustainability4
Producing a kilogram of A3 Nitrided takes about 36 MJ of energy and emits 2.6 kg of CO₂ — more than 89% of steel grades. Typical recycled content is 30%.
Manufacturability8
A3 Nitrided's machinability is not recommended (5/100, worse than 100% of steel grades); weldability not recommended (3/100); formability not recommended (2/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A3 Nitrided
Is A3 easy to machine?
Machine in the annealed condition with rigid setups, sharp carbide or cobalt HSS tooling and moderate speeds; the high vanadium carbide content accelerates tool and wheel wear, so allow generous grinding stock and finish by grinding after hardening.
Can A3 be welded?
Poor weldability — repair welding only, with 300–450 °C preheat, matching or Cr-Mo tool-steel filler, minimal heat input and an immediate temper at the previous tempering temperature.
Can A3 be formed, bent or molded?
Cold forming is impractical; hot work at 900–1050 °C with slow controlled cooling and full anneal (~845–870 °C, slow cool) afterwards; austenitize 940–970 °C, air quench, temper 175–540 °C — dimensional change on hardening is very small.
What surface finishes work on A3?
Not corrosion resistant: protect with oil, black oxide, phosphating, nitriding or PVD TiN/CrN; polishing is possible but coarse vanadium carbides limit true mirror finish.
A3 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 |
|---|---|---|
| CASTM A681 grade A3 | 1.2 – 1.3 | 1.25 |
| Mn | 0.4 – 0.6 | 0.5 |
| Si | ≤ 0.5 | 0.3 |
| Cr | 4.75 – 5.5 | 5.1 |
| Mo | 0.9 – 1.4 | 1.1 |
| Vhigh V gives extra wear resistance vs A2 | 0.8 – 1.4 | 1 |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Fe | balance | — |
A3 Nitrided — frequently asked
What is A3 Nitrided used for?
A3 Nitrided is typically used for blanking and piercing dies, forming and coining punches, trim dies and die inserts, shear and slitter blades, thread-rolling dies and cold-forming tooling. In short: air-hardening cold-work tool.
What is the yield strength of A3 Nitrided?
A3 Nitrided has a typical yield strength of 1,750 MPa (254 ksi) and a tensile strength of 2,000 MPa (290 ksi) — stronger than 99% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is A3 Nitrided easy to machine?
Not especially — machinability is rated not recommended (5/100, worse than 100% of steel grades). Machine in the annealed condition with rigid setups, sharp carbide or cobalt HSS tooling and moderate speeds; the high vanadium carbide content accelerates tool and wheel wear, so allow generous grinding stock and finish by grinding after hardening.
Can A3 Nitrided be welded?
Not readily — weldability is rated not recommended (3/100). Poor weldability — repair welding only, with 300–450 °C preheat, matching or Cr-Mo tool-steel filler, minimal heat input and an immediate temper at the previous tempering temperature.
What surface finishes work on A3 Nitrided?
Not corrosion resistant: protect with oil, black oxide, phosphating, nitriding or PVD TiN/CrN; polishing is possible but coarse vanadium carbides limit true mirror finish.
Can A3 Nitrided be formed, bent or molded?
Cold forming is impractical; hot work at 900–1050 °C with slow controlled cooling and full anneal (~845–870 °C, slow cool) afterwards; austenitize 940–970 °C, air quench, temper 175–540 °C — dimensional change on hardening is very small.
What is the maximum service temperature of A3 Nitrided?
A3 Nitrided 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.
Can FabDigit make parts in A3 Nitrided?
Yes — A3 Nitrided 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
- ASTM A681 — Standard Specification for Tool Steels Alloy — ASTM International (2022)
- SAE J437/J438 — Tool and Die Steels — SAE International (2015)
- ASM Handbook Vol.1: Properties and Selection: Irons, Steels, and High-Performance Alloys (Tool Steels) — ASM International (1990)
- ASM Specialty Handbook: Tool Materials — ASM International (1995)
- ASM Handbook Vol.16: Machining — ASM International (1989)
- Air-hardening cold work tool steel (A2/A3 class) datasheets — Böhler / Crucible Industries (2020)
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.