Steel A8 · heat-treated state
Steel A8 Hardened & Tempered
Properties of the Hardened & Tempered condition, compared with the other A8 tempers.
Use when the tool is delivered hardened but the exact hardness band is set by the toolmaker.
What is A8 Hardened & Tempered?
A8 Hardened & Tempered is A8 heat treated to Hardened & Tempered — use when the tool is delivered hardened but the exact hardness band is set by the toolmaker. A8 Hardened & Tempered has a yield strength of 500 MPa (72.5 ksi) and a tensile strength of 1,950 MPa (283 ksi) — stronger than 63% of steel grades. Elongation at break is 18% and the elastic modulus is 207 GPa (30 Msi). A8 Hardened & Tempered has a density of 7.83 g/cm³ (0.283 lb/in³), lighter than 80% of steel grades. It melts at 1,420°C (2,588 °F). Annealed is the default condition FabDigit quotes; Hardened & Tempered is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Difficult to machine — 10/100, worse than 100% of steel grades
- Low electrical conductivity — 2.9 % IACS, worse than 93% of steel grades
- Poor heat conductor — 24.5 W/m·K (14.2 BTU/hr·ft·°F), worse than 89% of steel grades
- High embodied carbon — 2.6 kg CO₂/kg, worse than 86% of steel grades
- Difficult to weld — 20/100, worse than 84% of steel grades
A8 Hardened & Tempered properties
Typical room-temperature values for A8 Hardened & Tempered — 8 properties are specific to this condition; the rest are grade-level values shared by every A8 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
A8 Hardened & Tempered has a density of 7.83 g/cm³ (0.283 lb/in³), lighter than 80% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical13
A8 Hardened & Tempered has a yield strength of 500 MPa (72.5 ksi) and a tensile strength of 1,950 MPa (283 ksi) — stronger than 63% of steel grades. Elongation at break is 18% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
A8 Hardened & Tempered is rated for continuous service to 425°C (797 °F). It conducts heat at 24.5 W/m·K (14.2 BTU/hr·ft·°F), worse than 89% of steel grades. Thermal expansion is 12.4 µm/m·K (6.89 µin/in·°F).
Electrical3
A8 Hardened & Tempered conducts electricity at 2.9 % IACS, worse than 93% of steel grades.
Chemical & Environmental2
Corrosion resistance is poor (20/100), better than 87% of steel grades.
Sustainability4
Producing a kilogram of A8 Hardened & Tempered takes about 34 MJ of energy and emits 2.6 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 40%.
Manufacturability7
A8 Hardened & Tempered's machinability is not recommended (10/100, worse than 100% of steel grades); weldability poor (20/100); formability poor (20/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other A8 tempers and conditions
A8 is also supplied in 6 other conditions. The full side-by-side table is on the A8 overview.
- AnnealedDefaultStandard stock condition for machining dies and inserts before hardening.500 MPa yield · 220 HB
- Hardened & TemperedUse when the tool is delivered hardened but the exact hardness band is set by the toolmaker.1,950 MPa tensile
- H&T 60-62 HRCChoose for thin-stock blanking punches and wear inserts where abrasion, not impact, dominates.1,850 MPa yield · 61 HRC
- Q&TGeneral working condition: good balance of toughness and wear for blanking and forming tools.1,700 MPa yield · 59 HRC
- H&T 58-60 HRCThe usual compromise between wear resistance and toughness for blanking and forming dies.1,700 MPa yield · 59 HRC
- H&T 56-58 HRCPick for heavy shear blades, thick-section punches and impact-loaded dies where chipping is the failure mode.1,600 MPa yield · 57 HRC
Working with A8 Hardened & Tempered
Is A8 easy to machine?
Machine only in the annealed state (~220 HB) with rigid setups and coated carbide; after hardening use grinding or EDM plus a stress-relief temper.
Can A8 be welded?
Weld only for repair — preheat 300–370 °C, use matched 5 % Cr tool-steel filler, keep interpass temperature and temper immediately below the last tempering temperature.
Can A8 be formed, bent or molded?
Hot work at 1050–900 °C followed by slow cooling; no meaningful cold forming — air harden from 980–1010 °C with minimal size change and double temper at 200–540 °C.
What surface finishes work on A8?
Takes a good ground/lapped finish; protect with oil, black oxide, nitriding or PVD TiN/CrN coatings since the 5 % Cr gives no stainless behaviour.
A8 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 | 0.5 – 0.6 | 0.55 |
| Mn | 0.2 – 0.5 | 0.35 |
| Si | 0.75 – 1.1 | 0.95 |
| Cr | 4.75 – 5.5 | 5.1 |
| Mo | 1.15 – 1.65 | 1.3 |
| W | 1 – 1.5 | 1.25 |
| Voptional/residual per ASTM A681 | ≤ 0.25 | 0.2 |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Fe | balance | — |
A8 Hardened & Tempered — frequently asked
What is A8 Hardened & Tempered used for?
A8 Hardened & Tempered is typically used for cold-work blanking and forming dies, slitter knives, shear blades, punches and die inserts, trim and pierce tooling and cold-forming die inserts for shock loading. In short: air-hardening tool steel.
What is the yield strength of A8 Hardened & Tempered?
A8 Hardened & Tempered has a typical yield strength of 500 MPa (72.5 ksi) and a tensile strength of 1,950 MPa (283 ksi) — stronger than 63% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is A8 Hardened & Tempered easy to machine?
Not especially — machinability is rated not recommended (10/100, worse than 100% of steel grades). Machine only in the annealed state (~220 HB) with rigid setups and coated carbide; after hardening use grinding or EDM plus a stress-relief temper.
Can A8 Hardened & Tempered be welded?
Not readily — weldability is rated poor (20/100). Weld only for repair — preheat 300–370 °C, use matched 5 % Cr tool-steel filler, keep interpass temperature and temper immediately below the last tempering temperature.
What surface finishes work on A8 Hardened & Tempered?
Takes a good ground/lapped finish; protect with oil, black oxide, nitriding or PVD TiN/CrN coatings since the 5 % Cr gives no stainless behaviour.
Can A8 Hardened & Tempered be formed, bent or molded?
Hot work at 1050–900 °C followed by slow cooling; no meaningful cold forming — air harden from 980–1010 °C with minimal size change and double temper at 200–540 °C.
What is the maximum service temperature of A8 Hardened & Tempered?
A8 Hardened & Tempered is rated for continuous use to about 425°C (797 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in A8 Hardened & Tempered?
Yes — A8 Hardened & Tempered is available for CNC machining with instant online pricing. Upload a STEP file to get a price and a DFM check.
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 ed. (Roberts, Krauss, Kennedy) — ASM International (1998)
- A8 air-hardening cold-work tool steel datasheet — Tool-steel producers (Crucible/Latrobe/Böhler-type data) (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.