Steel A10-HR (Hot rolled)
Supply condition
AISI/SAE A10 · UNS T30110
Use hot-rolled or as-forged bar only as raw stock: hardness is uneven around 300 HB, so graphitizing annealing is mandatory before any machining.
Values for the HR condition
Other A10 tempers and conditions
A10 is listed in 5 conditions; see the grade overview at A10.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ANNDefault Annealed | Default supply and machining state: spheroidize/graphitize annealed to ≤235 HB with graphite precipitated, so cutting and drilling run well before air hardening. | 450 | 720 | 18 | 229 HB | — |
HRThis page Hot rolled | Use hot-rolled or as-forged bar only as raw stock: hardness is uneven around 300 HB, so graphitizing annealing is mandatory before any machining. | 620 | 950 | 10 | 31 HRC | 3 % IACS |
Hardened & tempered ~340–400 °C | Choose the ~340–400 °C temper for punches and guide plates under heavier impact, accepting 54–56 HRC and shorter wear life for 5 % elongation. | 1,550 | 1,800 | 5 | 55 HRC | — |
Hardened & tempered ~230–290 °C | Use the ~230–290 °C temper to trade a few hardness points for toughness at 57–59 HRC, the general-purpose working hardness for cold-work tooling. | 1,650 | 1,950 | 3 | 58 HRC | — |
Hardened & low-temper | Pick after 790–815 °C austenitizing, air cooling and a 150–200 °C temper for maximum 60–62 HRC hardness in wear- and galling-resistant cold-work dies and punches; machinability falls to 15. | 1,750 | 2,100 | 2 | 61 HRC | — |
What is A10-HR?
A10-HR is A10 supplied in the HR condition — use hot-rolled or as-forged bar only as raw stock: hardness is uneven around 300 HB, so graphitizing annealing is mandatory before any machining. A10-HR has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 78% of steel grades. Elongation at break is 10% and the elastic modulus is 190 GPa (27.6 Msi). A10-HR has a density of 7.34 g/cm³ (0.265 lb/in³), lighter than 98% of steel grades. It melts at 1,400°C (2,552 °F). ANN is the default condition FabDigit quotes; HR is available on request or by drawing note.
Advantages
- High strength — 620 MPa (89.9 ksi), better than 78% of steel grades
Limitations
- Difficult to weld — 10/100, worse than 99% of steel grades
- Limited formability — 8/100, worse than 97% of steel grades
- Hard to polish — 40/100, worse than 96% of steel grades
- Limited ductility — 10%, worse than 91% of steel grades
- Low electrical conductivity — 3 % IACS, worse than 91% of steel grades
A10-HR properties
Typical room-temperature values for A10-HR; 23 are specific to this condition. Other listed values are A10 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
A10-HR has a density of 7.34 g/cm³ (0.265 lb/in³), lighter than 98% of steel grades. It melts at 1,400°C (2,552 °F).
Mechanical15
A10-HR has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 78% of steel grades. Elongation at break is 10% and the elastic modulus is 190 GPa (27.6 Msi).
Thermal6
A10-HR 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 µm/m·K (6.67 µin/in·°F).
Electrical3
A10-HR conducts electricity at 3 % IACS, worse than 91% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of A10-HR takes about 36 MJ of energy and emits 2.6 kg of CO₂ — more than 89% of steel grades. Typical recycled content is 35%.
Manufacturability8
A10-HR's machinability is fair (40/100, worse than 77% of steel grades); weldability not recommended (10/100); formability not recommended (8/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A10-HR
Is A10 easy to machine?
In the annealed state the free graphite acts as an internal lubricant, so turning, milling, drilling and tapping are easier than in other tool steels of similar carbon level, with short chips and long tool life. Once hardened, use CBN grinding or hard turning.
Can A10 be welded?
Crack risk is high in this high-carbon air-hardening steel; limit welding to small repairs with matching die-repair wire at low current, preheat 300–400 °C and temper immediately afterwards.
Can A10 be formed, bent or molded?
Only light cold forming or straightening in the annealed condition. Hot work at about 1010–1120 °C, finish forging no lower than 900 °C, cool slowly and graphitize anneal promptly.
What surface finishes work on A10?
Not anodizable; use black oxide, phosphate, chrome plating or low-temperature PVD applied at or below the tempering temperature. Graphite particles leave micro-pits when polishing, so switch to A2 or D2 where a mirror surface is required.
A10 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 |
|---|---|---|
| Cpartly present as free graphite | 1.25 – 1.5 | 1.35 |
| Sipromotes graphitization | 1 – 1.5 | 1.25 |
| Mn | 1.6 – 2.1 | 1.8 |
| Niincreases hardenability, promotes graphitization | 1.55 – 2.05 | 1.8 |
| Mo | 1.25 – 1.75 | 1.5 |
| Crresidual; excess suppresses graphite formation | ≤ 0.35 | 0.15 |
| Pimpurity limit | ≤ 0.03 | — |
| Simpurity limit | ≤ 0.03 | — |
| Fe | balance | — |
A10-HR — frequently asked
What is A10-HR used for?
A10-HR is typically used for blanking dies, coining dies and wear parts needing anti-galling. In short: self-lubricating graphitic tool steel; best anti-galling cold-work grade; air-hardening, low distortion.
What is the yield strength of A10-HR?
A10-HR has a typical yield strength of 620 MPa (89.9 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 78% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is A10-HR easy to machine?
Not especially — machinability is rated fair (40/100, worse than 77% of steel grades). In the annealed state the free graphite acts as an internal lubricant, so turning, milling, drilling and tapping are easier than in other tool steels of similar carbon level, with short chips and long tool life. Once hardened, use CBN grinding or hard turning.
Can A10-HR be welded?
Not readily — weldability is rated not recommended (10/100). Crack risk is high in this high-carbon air-hardening steel; limit welding to small repairs with matching die-repair wire at low current, preheat 300–400 °C and temper immediately afterwards.
What surface finishes work on A10-HR?
Not anodizable; use black oxide, phosphate, chrome plating or low-temperature PVD applied at or below the tempering temperature. Graphite particles leave micro-pits when polishing, so switch to A2 or D2 where a mirror surface is required.
Can A10-HR be formed, bent or molded?
Only light cold forming or straightening in the annealed condition. Hot work at about 1010–1120 °C, finish forging no lower than 900 °C, cool slowly and graphitize anneal promptly.
What is the maximum service temperature of A10-HR?
A10-HR 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 A10-ANN and A10-HR?
ANN is the default condition — default supply and machining state: spheroidize/graphitize annealed to ≤235 HB with graphite precipitated, so cutting and drilling run well before air hardening. HR: use hot-rolled or as-forged bar only as raw stock: hardness is uneven around 300 HB, so graphitizing annealing is mandatory before any machining. Yield strength is 450 MPa in ANN versus 620 MPa in HR.
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)
- ASM Handbook Vol.16: Machining — machinability ratings of tool steels — ASM International (1989)
- UNS T30110 / AISI A10 tool steel property records — SAE/ASTM 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.