Steel A3
AISI/SAE A3 · UNS T30103
A3 (UNS T30103) is a higher-carbon, vanadium-alloyed air-hardening cold-work tool steel from the AISI A group, using vanadium carbides to give greater wear resistance than A2 on long-run dies.
Values for the Annealed condition
A3 tempers and conditions
A3 is supplied in 6 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
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 | — |
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?
A3 (UNS T30103) is a higher-carbon, vanadium-alloyed air-hardening cold-work tool steel from the AISI A group, using vanadium carbides to give greater wear resistance than A2 on long-run dies. It is bought as annealed bar and plate (about 217 HB, 19 HRC, 760 MPa tensile) for machining, then hardened and tempered to 56–58, 58–60 or 60–62 HRC; nitrided and stress-relieved conditions are also on file. Air hardening keeps dimensional change very small, but the grade is not corrosion resistant, is limited to about 200 °C service, welds poorly, and the vanadium carbides cut tool and wheel life — A2 is the easier alternative when peak wear resistance is not required. A3 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). A3 has a yield strength of 430 MPa (62.4 ksi) and a tensile strength of 760 MPa (110 ksi) — weaker than 51% of steel grades. Elongation at break is 20% and the elastic modulus is 203 GPa (29.4 Msi).
What is A3 used for?
- Blanking and piercing dies
- Forming and coining punches
- Trim dies and die inserts
- Shear and slitter blades
- Thread-rolling dies
- Cold-forming tooling
- Gauges and mandrels
Advantages
- Polishes to a fine finish — 70/100, better than 87% of steel grades
Limitations
- Low electrical conductivity — 2.7 % IACS, worse than 96% of steel grades
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
- Difficult to weld — 15/100, worse than 91% of steel grades
- Poor heat conductor — 24 W/m·K (13.9 BTU/hr·ft·°F), worse than 90% of steel grades
- High embodied carbon — 2.6 kg CO₂/kg, worse than 87% of steel grades
A3 properties
Typical room-temperature values for A3-Annealed; bars are the position among steel grades.
Physical3
A3 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 has a yield strength of 430 MPa (62.4 ksi) and a tensile strength of 760 MPa (110 ksi) — weaker than 51% of steel grades. Elongation at break is 20% and the elastic modulus is 203 GPa (29.4 Msi).
Thermal6
A3 is rated for continuous service to 200°C (392 °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 conducts electricity at 2.7 % IACS, worse than 96% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (16/100), better than 79% of steel grades.
Sustainability4
Producing a kilogram of A3 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's machinability is fair (38/100, worse than 80% of steel grades); weldability poor (15/100); formability poor (20/100).
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. A3 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with A3
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.
Manufacturability
The process limits FabDigit applies to A3. Every A3 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Fair38 / 100 |
|---|---|
| ISO material group | P.2 |
| Cutting speed (rough / finish) | 175 / 205 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 |
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 |
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.
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
Equivalent designations
Standards and trade names that resolve to Steel A3 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- T30103
- Also called
- A3 Tool SteelAir-Hardening Tool Steel
How much does A3 cost?
A3 is a premium-cost steel ($$$), cheaper than about 58% 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.
A3 — frequently asked
What is A3 used for?
A3 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?
A3 has a typical yield strength of 430 MPa (62.4 ksi) and a tensile strength of 760 MPa (110 ksi) — weaker than 51% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is A3 easy to machine?
Not especially — machinability is rated fair (38/100, worse than 80% 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 be welded?
Not readily — weldability is rated poor (15/100). 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?
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 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?
A3 is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does A3 cost?
A3 is a premium-cost steel ($$$), cheaper than about 58% 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 A3?
Yes — A3 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; 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.