Steel T8
AISI/SAE T8 · UNS T12008
T8 (T12008) is a tungsten-type high-speed steel with reduced tungsten content (14%) and a cobalt addition, trading some red hardness for toughness compared with higher-tungsten T grades.
Values for the Annealed condition
T8 tempers and conditions
T8 is supplied in 5 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault soft annealed bar/billet, ≤277 HB | Standard stocked condition for machining tool blanks before hardening. | 570 | 900 | 15 | 240 HB | — |
Cold drawn annealed bar / drill rod | Pick for small-diameter precision bar and drill-rod blanks needing close size and straightness before hardening. | 750 | 1,000 | 9 | 28 HRC | 3.1 % IACS |
Maximum hardness, low-temperature-limit temper | Use only for rigid, continuous-cut tooling on abrasive work where maximum wear resistance outweighs chipping risk. | 2,000 | 2,100 | 0 | 67 HRC | 2.8 % IACS |
Hardened and high-temperature tempered | Choose when interrupted cuts or shock demand extra toughness at some loss of wear resistance. | 2,100 | 0.5 | 63 HRC | — | |
Hardened (1230–1260 °C) and double tempered ~550 °C | The normal working hardness for T8 cutting tools — best balance of red hardness and wear resistance. | 2,250 | 0.3 | 65 HRC | — |
Supply forms, finishes and certifications
Ways T8 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
HT+Surface | HT + surface treated | Surface finish |
What is T8?
T8 (T12008) is a tungsten-type high-speed steel with reduced tungsten content (14%) and a cobalt addition, trading some red hardness for toughness compared with higher-tungsten T grades. It is used for general-purpose high-speed cutting tools and cold cutting tooling at moderate heat, supplied annealed, cold-drawn-annealed, or heat treated to 62–64, 64–66 or 66–67 HRC with optional surface treatment; annealed bar runs about 240 HB, 900 MPa tensile and 570 MPa yield. Service temperature is limited to roughly 400 °C, machinability is low so hardened parts must be ground or EDM'd, and the steel offers no corrosion resistance. T8 has a density of 8.6 g/cm³ (0.311 lb/in³), heavier than 99% of steel grades. It melts at 1,400°C (2,552 °F). T8 has a yield strength of 570 MPa (82.7 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 74% of steel grades. Elongation at break is 15% and the elastic modulus is 220 GPa (31.9 Msi).
What is T8 used for?
- Cold cutting knives and blades
- Hand tools
- Lathe tool bits and form tools
- Milling cutters
- Twist drills and taps
- Punches and trim dies
- Reamers and broaches
Advantages
- Polishes to a fine finish — 70/100, better than 87% of steel grades
Limitations
- High embodied carbon — 4.2 kg CO₂/kg, worse than 95% of steel grades
- Poor heat conductor — 22 W/m·K (12.7 BTU/hr·ft·°F), worse than 93% of steel grades
- Limited formability — 12/100, worse than 92% of steel grades
- Difficult to weld — 15/100, worse than 91% of steel grades
- Low electrical conductivity — 3.1 % IACS, worse than 89% of steel grades
T8 properties
Typical room-temperature values for T8-Annealed; bars are the position among steel grades.
Physical3
T8 has a density of 8.6 g/cm³ (0.311 lb/in³), heavier than 99% of steel grades. It melts at 1,400°C (2,552 °F).
Mechanical13
T8 has a yield strength of 570 MPa (82.7 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 74% of steel grades. Elongation at break is 15% and the elastic modulus is 220 GPa (31.9 Msi).
Thermal6
T8 is rated for continuous service to 400°C (752 °F). It conducts heat at 22 W/m·K (12.7 BTU/hr·ft·°F), worse than 93% of steel grades. Thermal expansion is 11.2 µm/m·K (6.22 µin/in·°F).
Electrical3
T8 conducts electricity at 3.1 % IACS, worse than 89% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (18/100), better than 83% of steel grades.
Sustainability4
Producing a kilogram of T8 takes about 60 MJ of energy and emits 4.2 kg of CO₂ — more than 96% of steel grades. Typical recycled content is 35%.
Manufacturability7
T8's machinability is fair (35/100, worse than 84% of steel grades); weldability poor (15/100); formability not recommended (12/100).
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. T8 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with T8
Is T8 easy to machine?
Machine only in the annealed condition with rigid setups, sharp carbide or cobalt-HSS tooling, low speed and heavy flood coolant; hardened T8 must be ground or EDM'd, using soft wheels and light dressing to avoid grinding burn.
Can T8 be welded?
Not a structural welding grade — repair only, by GTAW/PTA with matching HSS or high-Co filler, preheat 500–550 °C, immediate re-temper; expect cracking if cooled to room temperature unbuffered.
Can T8 be formed, bent or molded?
Hot work at 1050–1150 °C with slow furnace cooling and mandatory full anneal (~870 °C, slow cool) afterwards; no meaningful cold forming — harden from 1230–1260 °C (salt or vacuum), oil/air/salt quench, double temper 540–595 °C.
Manufacturability
The process limits FabDigit applies to T8. Every T8 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Better35 / 100 |
|---|---|
| ISO material group | P.2 |
| Cutting speed (rough / finish) | 180 / 210 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 |
T8 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 | 0.75 – 0.85 | 0.8 |
| W | 13.25 – 14.75 | 14 |
| Co | 4.25 – 5.75 | 5 |
| Cr | 3.75 – 4.5 | 4.1 |
| V | 1.8 – 2.4 | 2 |
| Mo | 0.4 – 1 | 0.7 |
| Mn | 0.15 – 0.4 | 0.28 |
| Si | 0.15 – 0.4 | 0.28 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on T8?
Stress-relieve rough-machined blanks before hardening; finish by precision grinding and lapping, then steam-oxide, black-oxide, nitriding or TiN/TiAlN PVD (below temper temperature) for wear and rust protection — never anodise.
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 T8 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- T12008
How much does T8 cost?
T8 is a premium-cost steel ($$$), pricier than about 57% 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.
T8 — frequently asked
What is T8 used for?
T8 is typically used for cold cutting knives and blades, hand tools, lathe tool bits and form tools, milling cutters, twist drills and taps and punches and trim dies. In short: tough water-hardening tool.
What is the yield strength of T8?
T8 has a typical yield strength of 570 MPa (82.7 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 74% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is T8 easy to machine?
Not especially — machinability is rated fair (35/100, worse than 84% of steel grades). Machine only in the annealed condition with rigid setups, sharp carbide or cobalt-HSS tooling, low speed and heavy flood coolant; hardened T8 must be ground or EDM'd, using soft wheels and light dressing to avoid grinding burn.
Can T8 be welded?
Not readily — weldability is rated poor (15/100). Not a structural welding grade — repair only, by GTAW/PTA with matching HSS or high-Co filler, preheat 500–550 °C, immediate re-temper; expect cracking if cooled to room temperature unbuffered.
What surface finishes work on T8?
Stress-relieve rough-machined blanks before hardening; finish by precision grinding and lapping, then steam-oxide, black-oxide, nitriding or TiN/TiAlN PVD (below temper temperature) for wear and rust protection — never anodise.
Can T8 be formed, bent or molded?
Hot work at 1050–1150 °C with slow furnace cooling and mandatory full anneal (~870 °C, slow cool) afterwards; no meaningful cold forming — harden from 1230–1260 °C (salt or vacuum), oil/air/salt quench, double temper 540–595 °C.
What is the maximum service temperature of T8?
T8 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 T8 Annealed and T8-CDA?
Annealed is the default condition — standard stocked condition for machining tool blanks before hardening. CDA: pick for small-diameter precision bar and drill-rod blanks needing close size and straightness before hardening. Yield strength is 570 MPa in Annealed versus 750 MPa in CDA.
How much does T8 cost?
T8 is a premium-cost steel ($$$), pricier than about 57% 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 T8?
Yes — T8 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 A600 — Tool Steel, High Speed, Tool and Die Steels — ASTM International (2016)
- ASM Handbook Vol. 1: Properties and Selection — Irons, Steels, and High-Performance Alloys (High Speed Tool Steels) — ASM International (1990)
- ASM Specialty Handbook: Tool Materials — ASM International (1995)
- SAE J437/J438 — Tool and Die Steels — SAE International (2015)
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.