Steel T7A
GB T7A
T7A is a plain carbon tool steel with about 0.7 % C from the GB T7–T13 / JIS SK family, supplied to the high-purity (A) specification and hardened by water or oil quenching.
Reference datasheet — T7A 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
T7A tempers and conditions
T7A is supplied in 9 conditions, soft to hard. A is the default FabDigit quotes; the values on this page are for it.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ADefault Solution annealed | Standard mill-supplied soft condition for machining and forming before hardening. | 380 | 660 | 22 | 180 HB | 48 W/m·K |
Hot rolled | Cheapest mill form for forging stock; harder and less uniform than annealed, normally annealed before machining. | 430 | 780 | 15 | 19 HRC | 9.3 % IACS |
Normalized | Grain refinement of forgings before final anneal or hardening. | 450 | 830 | 14 | 22 HRC | 9.2 % IACS |
Cold drawn | Choose for close-tolerance bright bar going straight into automatic machining before hardening. | 570 | 750 | 10 | 16 HRC | 9.4 % IACS |
Q&T 42–48 HRC | Toughest hardened condition, used for heavily loaded striking tools and spring-like tool sections. | 1,250 | 1,450 | 8 | 45 HRC | — |
Q&T 50–54 HRC | The classic impact-tool condition for hammers, riveting sets and rock drills where shock beats wear. | 1,450 | 1,750 | 5 | 52 HRC | — |
Q&T 54–57 HRC | Balanced hardness/toughness for cold chisels, punches and shear blades. | 1,650 | 1,950 | 2 | 56 HRC | 8 % IACS |
As-Quenched | Untempered reference condition proving hardenability; must be tempered immediately to avoid cracking. | 1,800 | 2,200 | 0.5 | 63 HRC | 7.8 % IACS |
Q&T 57–60 HRC | Maximum wear resistance condition for wood chisels, files and light punches on thin sections. | 2,100 | 58 HRC | — |
What is T7A?
T7A is a plain carbon tool steel with about 0.7 % C from the GB T7–T13 / JIS SK family, supplied to the high-purity (A) specification and hardened by water or oil quenching. It keeps toughness at moderate hardness, so it is used for impact-tolerant hand tools, and is available as annealed, hot-rolled, cold-drawn and normalized bar and strip plus quench-and-temper bands from 42–48 HRC to 57–60 HRC. Annealed values are 380 MPa yield, 660 MPa tensile, 22 % elongation and 180 HB, with 48 W/m·K conductivity and service to 300 °C. Hardening is shallow, corrosion resistance nil and welding poor; T8A gives more edge hardness where impact loading is lower. T7A 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). T7A has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 660 MPa (95.7 ksi) — weaker than 68% of steel grades. Elongation at break is 22% and the elastic modulus is 207 GPa (30 Msi).
What is T7A used for?
- chisels
- hammers
- punches
- hand tools
Advantages
- Easy to machine — 62/100, better than 89% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
- 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 — 20/100, worse than 84% of steel grades
- Limited service temperature — 300°C (572 °F), worse than 78% of steel grades
T7A properties
Typical room-temperature values for T7A-A; bars are the position among steel grades.
Physical3
T7A 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).
Mechanical15
T7A has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 660 MPa (95.7 ksi) — weaker than 68% of steel grades. Elongation at break is 22% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
T7A 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
T7A 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 T7A takes about 26 MJ of energy and emits 2.1 kg of CO₂ — less than 64% of steel grades. Typical recycled content is 25%.
Manufacturability8
T7A's machinability is good (62/100, better than 89% of steel grades); weldability poor (20/100); formability fair (45/100).
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. T7A is highlighted; hover a dot for its name, or open the interactive family chart.
Working with T7A
Is T7A easy to machine?
Machine in the spheroidize-annealed condition (~180 HB, ~65 % of 1212); HSS works fine but carbide and rigid setups improve finish — grinding is the only practical route above 55 HRC.
Can T7A be welded?
Poor weldability at 0.7 % C: preheat 250–350 °C, use low-hydrogen or matching filler, and temper immediately after welding; avoid welding on finished tool edges.
Can T7A be formed, bent or molded?
Hot forge 1050–850 °C then slow cool and spheroidize anneal at 730–750 °C; cold bending only in the annealed state with generous radii.
T7A 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 |
|---|---|---|
| CGB/T 1298 T7/T7A | 0.65 – 0.74 | 0.7 |
| Si | ≤ 0.35 | 0.2 |
| Mn | ≤ 0.4 | 0.25 |
| Pgrade A high-quality, tighter than T7 (0.035) | ≤ 0.03 | |
| Sgrade A high-quality, tighter than T7 (0.030) | ≤ 0.02 | |
| Crresidual | ≤ 0.25 | |
| Niresidual | ≤ 0.2 | |
| Curesidual | ≤ 0.3 | |
| Fe | balance |
What surface finishes work on T7A?
No corrosion resistance — protect with oil, black oxide, phosphate, or hard chrome; hardened surfaces polish well but must be kept below the tempering temperature during grinding.
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 T7A cost?
T7A 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.
T7A — frequently asked
What is T7A used for?
T7A is typically used for chisels, hammers, punches and hand tools. In short: toughest carbon tool steel; impact tools over cutting edges; shallow hardening only.
What is the yield strength of T7A?
T7A has a typical yield strength of 380 MPa (55.1 ksi) and a tensile strength of 660 MPa (95.7 ksi) — weaker than 68% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is T7A easy to machine?
Reasonably — machinability is rated good (62/100, better than 89% of steel grades). Machine in the spheroidize-annealed condition (~180 HB, ~65 % of 1212); HSS works fine but carbide and rigid setups improve finish — grinding is the only practical route above 55 HRC.
Can T7A be welded?
Not readily — weldability is rated poor (20/100). Poor weldability at 0.7 % C: preheat 250–350 °C, use low-hydrogen or matching filler, and temper immediately after welding; avoid welding on finished tool edges.
What surface finishes work on T7A?
No corrosion resistance — protect with oil, black oxide, phosphate, or hard chrome; hardened surfaces polish well but must be kept below the tempering temperature during grinding.
Can T7A be formed, bent or molded?
Hot forge 1050–850 °C then slow cool and spheroidize anneal at 730–750 °C; cold bending only in the annealed state with generous radii.
What is the maximum service temperature of T7A?
T7A 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 T7A-A and T7A-AQ?
A is the default condition — standard mill-supplied soft condition for machining and forming before hardening. AQ: untempered reference condition proving hardenability; must be tempered immediately to avoid cracking. Yield strength is 380 MPa in A versus 1,800 MPa in AQ.
How much does T7A cost?
T7A 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
- JIS G 4401 Carbon Tool Steels (SK7) — JIS (2009)
- 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)
- T7A/T8A/T10A — Mysteel / 1688 (2025)
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.