Steel T8A
GB T8A
T8A is a plain carbon tool steel with about 0.8 % C from the GB T7–T13 / JIS SK family, sitting at the eutectoid composition so it hardens to a higher edge hardness than T7A.
Reference datasheet — T8A is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the A condition
T8A tempers and conditions
T8A is supplied in 10 conditions, soft to hard. A is the default FabDigit quotes; the values on this page are for it.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ADefault Solution annealed | Standard delivery condition for bar, flat and forging stock; soft and machinable, ready for hardening. | 375 | 620 | 24 | 179 HB | — |
Hot rolled | Cheapest mill condition for stock that will be annealed or hardened by the user. | 450 | 830 | 12 | 22 HRC | 46 W/m·K |
Cold drawn | Bright drawn bar or soft cold-rolled strip where dimensional accuracy and surface finish matter before hardening. | 520 | 700 | 12 | 200 HB | 48 W/m·K |
Normalized | Used to refine grain and break up network carbide in forgings before spheroidize annealing. | 520 | 950 | 11 | 30 HRC | 45 W/m·K |
Cold rolled hard strip | Work-hardened thin strip for shims, saw and blade blanks and light springs used without further heat treatment. | 850 | 1,000 | 3 | 28 HRC | 9.3 % IACS |
Quenched and tempered ~500 °C | Rarely used soft-tempered condition for spring or structural parts needing maximum ductility from this grade. | 1,150 | 1,350 | 9 | 42 HRC | — |
Quenched and tempered ~400 °C | Impact-dominated tooling and heavy-duty springs where toughness outweighs edge hardness. | 1,450 | 1,650 | 6 | 49 HRC | — |
Quenched and tempered ~300 °C | Tougher setting for punches, shear blades and cold chisels that take impact. | 1,650 | 1,950 | 3 | 56 HRC | — |
Water quenched from 780–800 °C, untempered | Intermediate as-quenched condition only — must be tempered immediately to avoid quench cracking. | 1,700 | 2,000 | 0.5 | 64 HRC | 7.5 % IACS |
Quenched and tempered 150–200 °C | Standard cutting-tool condition: maximum hardness and edge retention for wood chisels, files, razors and knives. | 1,900 | 2,200 | 1 | 61 HRC | — |
What is T8A?
T8A is a plain carbon tool steel with about 0.8 % C from the GB T7–T13 / JIS SK family, sitting at the eutectoid composition so it hardens to a higher edge hardness than T7A. It suits woodworking tools, cutting blades and small dies, and is supplied as annealed, hot-rolled, cold-drawn, cold-rolled hard and normalized bar and strip plus tempered conditions QT180 to QT500; annealed values are 375 MPa yield, 620 MPa tensile, 24 % elongation and 179 HB, with service to 300 °C. Hardening is shallow with a water or brine quench, formability and weldability are limited and the bare steel rusts; T10A is the next step for wear-dominated edges. T8A has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,400°C (2,552 °F). T8A has a yield strength of 375 MPa (54.4 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 70% of steel grades. Elongation at break is 24% and the elastic modulus is 210 GPa (30.5 Msi).
What is T8A used for?
- woodworking tools
- cutting blades
- small dies
Advantages
- Conducts heat well — 48 W/m·K (27.7 BTU/hr·ft·°F), better than 79% of steel grades
- High electrical conductivity — 9.5 % IACS, better than 75% of steel grades
Limitations
- Difficult to weld — 18/100, worse than 87% of steel grades
- Limited service temperature — 300°C (572 °F), worse than 78% of steel grades
T8A properties
Typical room-temperature values for T8A-A; bars are the position among steel grades.
Physical3
T8A has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,400°C (2,552 °F).
Mechanical15
T8A has a yield strength of 375 MPa (54.4 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 70% of steel grades. Elongation at break is 24% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
T8A is rated for continuous service to 300°C (572 °F). It conducts heat at 48 W/m·K (27.7 BTU/hr·ft·°F), better than 79% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
T8A conducts electricity at 9.5 % IACS, better than 75% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of T8A takes about 30 MJ of energy and emits 2.2 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 25%.
Manufacturability6
T8A's machinability is good (58/100, better than 75% of steel grades); weldability poor (18/100); formability fair (40/100).
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. T8A is highlighted; hover a dot for its name, or open the interactive family chart.
Working with T8A
Is T8A easy to machine?
Machine in the spheroidize-annealed state (≈65 % of AISI 1212); after hardening only grinding, EDM or superabrasive work is practical.
Can T8A be welded?
Poor weldability — high carbon gives hard, crack-prone martensite; if unavoidable preheat 250–300 °C, use low-hydrogen or high-nickel filler and temper immediately.
Can T8A be formed, bent or molded?
Cold form and bend only in the annealed/soft strip condition; hot forge 1050–850 °C followed by slow cooling and spheroidize anneal at 740–760 °C.
T8A 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 |
|---|---|---|
| Ceutectoid carbon level | 0.75 – 0.84 | 0.8 |
| Si | ≤ 0.35 | 0.2 |
| Mn | ≤ 0.4 | 0.25 |
| Ptighter than T8 (grade-A quality) | ≤ 0.03 | |
| Stighter than T8 (grade-A quality) | ≤ 0.02 | |
| Crresidual | ≤ 0.1 | |
| Niresidual | ≤ 0.12 | |
| Curesidual | ≤ 0.2 | |
| Fe | balance |
What surface finishes work on T8A?
Harden 780–800 °C water/brine quench then temper 150–200 °C; protect with oil, phosphate, black oxide or thin plating since the bare steel rusts quickly.
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).
Organic Coating
Black / Phosphate
Thermal Spray
How much does T8A cost?
T8A is a budget-cost steel ($), cheaper than about 90% 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.
T8A — frequently asked
What is T8A used for?
T8A is typically used for woodworking tools, cutting blades and small dies. In short: harder edge than T7A; low-cost cutting tool steel; water-hardening, distortion-prone.
What is the yield strength of T8A?
T8A has a typical yield strength of 375 MPa (54.4 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 70% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is T8A easy to machine?
Reasonably — machinability is rated good (58/100, better than 75% of steel grades). Machine in the spheroidize-annealed state (≈65 % of AISI 1212); after hardening only grinding, EDM or superabrasive work is practical.
Can T8A be welded?
Not readily — weldability is rated poor (18/100). Poor weldability — high carbon gives hard, crack-prone martensite; if unavoidable preheat 250–300 °C, use low-hydrogen or high-nickel filler and temper immediately.
What surface finishes work on T8A?
Harden 780–800 °C water/brine quench then temper 150–200 °C; protect with oil, phosphate, black oxide or thin plating since the bare steel rusts quickly.
Can T8A be formed, bent or molded?
Cold form and bend only in the annealed/soft strip condition; hot forge 1050–850 °C followed by slow cooling and spheroidize anneal at 740–760 °C.
What is the maximum service temperature of T8A?
T8A is rated for continuous use to about 300°C (572 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between T8A-A and T8A-QT180?
A is the default condition — standard delivery condition for bar, flat and forging stock; soft and machinable, ready for hardening. QT180: standard cutting-tool condition: maximum hardness and edge retention for wood chisels, files, razors and knives. Yield strength is 375 MPa in A versus 1,900 MPa in QT180.
How much does T8A cost?
T8A is a budget-cost steel ($), cheaper than about 90% 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.
Sources
- ASTM A686 Standard Specification for Carbon Tool Steel — ASTM International (2020)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating (water-hardening tool steels) — ASM International (1991)
- ASM Handbook Vol.16 — Machining — ASM International (1989)
- JIS G 4401 Carbon tool steels (SK85/SK5 equivalent) — JSA (2009)
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.