Steel A9-ANN (Annealed)
Heat-treated state · default condition
AISI/SAE A9 · UNS T30109
Standard mill supply condition for machining tool blanks before hardening.
Values for the ANN condition
Other A9 tempers and conditions
A9 is listed in 4 conditions; see the grade overview at A9.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ANNDefaultThis page Annealed | Standard mill supply condition for machining tool blanks before hardening. | 400 | 745 | 22 | 220 HB | — |
Hardened & tempered 44–48 HRC | Air-harden ~980–1010 °C, double temper ~590–620 °C when impact loading dominates over wear. | 1,300 | 1,500 | 8 | 46 HRC | — |
Hardened & tempered 50–52 HRC | Common working hardness for cold forming punches and heavy blanking dies with shock loading. | 1,550 | 1,750 | 5 | 51 HRC | — |
Hardened & secondary-hardened 54–56 HRC | Air quench ~1010 °C and double temper near 510–540 °C (secondary hardening peak) for abrasive cold-work tooling. | 1,750 | 1,950 | 3 | 55 HRC | — |
What is A9-ANN?
A9-ANN is A9 heat treated to ANN — standard mill supply condition for machining tool blanks before hardening. A9-ANN has a yield strength of 400 MPa (58 ksi) and a tensile strength of 745 MPa (108 ksi) — weaker than 60% of steel grades. Elongation at break is 22% and the elastic modulus is 200 GPa (29 Msi). A9-ANN has a density of 7.78 g/cm³ (0.281 lb/in³), lighter than 91% of steel grades. It melts at 1,420°C (2,588 °F).
Limitations
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
- Low electrical conductivity — 2.9 % IACS, worse than 93% 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 — 2.7 kg CO₂/kg, worse than 89% of steel grades
A9-ANN properties
Typical room-temperature values for A9-ANN; 17 are specific to this condition. Other listed values are A9 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
A9-ANN has a density of 7.78 g/cm³ (0.281 lb/in³), lighter than 91% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical15
A9-ANN has a yield strength of 400 MPa (58 ksi) and a tensile strength of 745 MPa (108 ksi) — weaker than 60% of steel grades. Elongation at break is 22% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
A9-ANN 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 11.8 µm/m·K (6.56 µin/in·°F).
Electrical3
A9-ANN conducts electricity at 2.9 % IACS, worse than 93% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (18/100), better than 83% of steel grades.
Sustainability4
Producing a kilogram of A9-ANN takes about 35 MJ of energy and emits 2.7 kg of CO₂ — more than 87% of steel grades. Typical recycled content is 45%.
Manufacturability8
A9-ANN's machinability is good (55/100, better than 62% of steel grades); weldability poor (30/100); formability poor (25/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A9-ANN
Is A9 easy to machine?
Machine in the annealed condition (~220 HB) with rigid setups and carbide tooling; vanadium carbides are abrasive, and above ~45 HRC only grinding or EDM is practical.
Can A9 be welded?
Repair-weld only: preheat 200–300 °C, use matching 5%Cr/Mo filler or Ni-base, keep interpass warm and temper immediately below the last tempering temperature.
Can A9 be formed, bent or molded?
Hot work at 1040–1120 °C and cool slowly; cold forming is limited to mild straightening in the annealed state — air hardening from 980–1010 °C gives minimal size change.
What surface finishes work on A9?
Stress relieve before finish grinding; nitriding, black oxide or PVD (TiN/CrN, deposited below the temper temperature) are used for wear and rust protection — no anodizing.
A9 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 | 0.45 – 0.55 | 0.5 |
| Mn | 0.2 – 0.8 | 0.5 |
| Siraises tempering resistance | 0.95 – 1.15 | 1.05 |
| Cr | 4.75 – 5.5 | 5.1 |
| Nitoughness / hardenability addition | 1.25 – 1.75 | 1.5 |
| Mosecondary hardening | 1.3 – 1.8 | 1.5 |
| Vgrain refinement, wear carbides | 0.8 – 1.4 | 1 |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Fe | balance | — |
A9-ANN — frequently asked
What is A9-ANN used for?
A9-ANN is typically used for die inserts subject to impact, cold forming dies, punches and trim tools. In short: tough air-hardening cold-work steel; S-series toughness, A-series stability; low distortion on hardening.
What is the yield strength of A9-ANN?
A9-ANN has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 745 MPa (108 ksi) — weaker than 60% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is A9-ANN easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machine in the annealed condition (~220 HB) with rigid setups and carbide tooling; vanadium carbides are abrasive, and above ~45 HRC only grinding or EDM is practical.
Can A9-ANN be welded?
Not readily — weldability is rated poor (30/100). Repair-weld only: preheat 200–300 °C, use matching 5%Cr/Mo filler or Ni-base, keep interpass warm and temper immediately below the last tempering temperature.
What surface finishes work on A9-ANN?
Stress relieve before finish grinding; nitriding, black oxide or PVD (TiN/CrN, deposited below the temper temperature) are used for wear and rust protection — no anodizing.
Can A9-ANN be formed, bent or molded?
Hot work at 1040–1120 °C and cool slowly; cold forming is limited to mild straightening in the annealed state — air hardening from 980–1010 °C gives minimal size change.
What is the maximum service temperature of A9-ANN?
A9-ANN 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.
Sources
- ASTM A681 Standard Specification for Tool Steels Alloy — ASTM International (2022)
- ASM Handbook Vol. 1: Properties and Selection — Irons, Steels and High-Performance Alloys (Tool Steels) — ASM International (1990)
- Tool Steels, 5th Edition (Roberts, Krauss, Kennedy) — ASM International (1998)
- UNS T30109 alloy record — SAE/ASTM Metals & Alloys in the Unified Numbering System (2017)
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.