Steel T8A-HR (Hot rolled)
Supply condition
GB T8A
Cheapest mill condition for stock that will be annealed or hardened by the user.
Values for the HR condition
Other T8A tempers and conditions
T8A is listed in 10 conditions; see the grade overview at T8A.
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 | — |
HRThis page 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-HR?
T8A-HR is T8A supplied in the HR condition — cheapest mill condition for stock that will be annealed or hardened by the user. T8A-HR has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 52% of steel grades. Elongation at break is 12% and the elastic modulus is 210 GPa (30.5 Msi). T8A-HR 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). A is the default condition FabDigit quotes; HR is available on request or by drawing note.
Advantages
- High electrical conductivity — 9.5 % IACS, better than 75% of steel grades
Limitations
- Difficult to weld — 15/100, worse than 91% of steel grades
- Limited ductility — 12%, worse than 84% of steel grades
- Limited service temperature — 300°C (572 °F), worse than 78% of steel grades
T8A-HR properties
Typical room-temperature values for T8A-HR; 20 are specific to this condition. Other listed values are T8A reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
T8A-HR 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-HR has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 52% of steel grades. Elongation at break is 12% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
T8A-HR is rated for continuous service to 300°C (572 °F). It conducts heat at 46 W/m·K (26.6 BTU/hr·ft·°F), better than 71% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
T8A-HR 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-HR 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-HR's machinability is fair (42/100, worse than 73% of steel grades); weldability poor (15/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with T8A-HR
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.
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.
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 | — |
T8A-HR — frequently asked
What is T8A-HR used for?
T8A-HR 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-HR?
T8A-HR has a typical yield strength of 450 MPa (65.3 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 52% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is T8A-HR easy to machine?
Not especially — machinability is rated fair (42/100, worse than 73% 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-HR be welded?
Not readily — weldability is rated poor (15/100). 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-HR?
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-HR 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-HR?
T8A-HR 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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.