Steel A656 Grade 80-QT (Quenched and tempered)
Heat-treated state
ASTM A656 Grade 80
Ordered for thick sections where as-rolled processing cannot reach 550 MPa yield, or when maximum toughness at 80 ksi is needed.
Values for the QT condition
Other A656 Grade 80 tempers and conditions
A656 Grade 80 is listed in 6 conditions; see the grade overview at A656 Grade 80.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Normalized | Used on heavier plate or when uniform through-thickness properties and stable toughness after forming are needed. | 580 | 670 | 20 | 15 HRC | 8.8 % IACS |
HRDefault Hot rolled | Standard stocked condition: hot-rolled, microalloy-strengthened plate meeting 550 MPa yield with good cold bending. | 590 | 680 | 18 | 17 HRC | 8.6 % IACS |
V + Nb (columbium) microalloyed chemistry | Chemistry option using vanadium and niobium precipitation strengthening; widely available and economical for general structural plate. | 590 | 685 | 17 | 19 HRC | 8.6 % IACS |
Ti microalloyed chemistry with sulfide shape control | Preferred where tight-radius cold bending and transverse ductility matter, e.g. truck bodies and crane booms. | 590 | 675 | 19 | 17 HRC | 8.6 % IACS |
Thermomechanically controlled processed | Choose when finer grain, better low-temperature toughness and lower carbon equivalent for welding are required at the same strength. | 610 | 700 | 20 | 18 HRC | 8.6 % IACS |
QTThis page Quenched and tempered | Ordered for thick sections where as-rolled processing cannot reach 550 MPa yield, or when maximum toughness at 80 ksi is needed. | 630 | 720 | 20 | 21 HRC | 8.4 % IACS |
What is A656 Grade 80-QT?
A656 Grade 80-QT is A656 Grade 80 heat treated to QT — ordered for thick sections where as-rolled processing cannot reach 550 MPa yield, or when maximum toughness at 80 ksi is needed. A656 Grade 80-QT has a yield strength of 630 MPa (91.4 ksi) and a tensile strength of 720 MPa (104 ksi) — stronger than 79% of steel grades. Elongation at break is 20% and the elastic modulus is 205 GPa (29.7 Msi). A656 Grade 80-QT has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,450°C (2,642 °F). HR is the default condition FabDigit quotes; QT is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 130 MPa·√m (118.3 ksi·√in), better than 89% of steel grades
- High strength — 630 MPa (91.4 ksi), better than 79% of steel grades
Limitations
- Hard to polish — 45/100, worse than 84% of steel grades
A656 Grade 80-QT properties
Typical room-temperature values for A656 Grade 80-QT; 24 are specific to this condition. Other listed values are A656 Grade 80 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
A656 Grade 80-QT has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,450°C (2,642 °F).
Mechanical17
A656 Grade 80-QT has a yield strength of 630 MPa (91.4 ksi) and a tensile strength of 720 MPa (104 ksi) — stronger than 79% of steel grades. Elongation at break is 20% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
A656 Grade 80-QT is rated for continuous service to 350°C (662 °F). It conducts heat at 43 W/m·K (24.8 BTU/hr·ft·°F), better than 51% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
A656 Grade 80-QT conducts electricity at 8.4 % IACS, better than 62% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of A656 Grade 80-QT takes about 25 MJ of energy and emits 2.1 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 25%.
Manufacturability7
A656 Grade 80-QT's machinability is fair (44/100, worse than 71% of steel grades); weldability very good (70/100); formability good (58/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A656 Grade 80-QT
Is A656 Grade 80 easy to machine?
Machines like a 550 MPa HSLA steel — rigid setups, sharp carbide tooling, moderate speeds; plasma/laser cut edges should be dressed before drilling to avoid hard cut-edge layers.
Can A656 Grade 80 be welded?
Readily weldable with low-hydrogen SMAW/FCAW/GMAW (E80/E81 class consumables); control heat input and preheat thicker plate to limit HAZ softening and hydrogen cracking.
Can A656 Grade 80 be formed, bent or molded?
Cold formable with generous bend radii (typically 2–3 t transverse); bend across the rolling direction and allow for high springback compared with mild steel.
What surface finishes work on A656 Grade 80?
Not anodizable — blast off mill scale then paint, zinc-rich prime, powder coat or hot-dip galvanize; galvanizing bath temperature can slightly relax as-rolled strength.
A656 Grade 80 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 |
|---|---|---|
| Cmax per ASTM A656 Types 3 and 7 | ≤ 0.18 | 0.1 |
| Mn | ≤ 1.65 | 1.4 |
| P | ≤ 0.03 | 0.01 |
| Skept very low with sulfide shape control for formability | ≤ 0.04 | 0.01 |
| Si | ≤ 0.6 | 0.3 |
| Algrain-refining / deoxidation, killed steel | ≥ 0.02 | 0.04 |
| VType 3 microalloying | 0.01 – 0.15 | 0.06 |
| NbType 3 microalloying (columbium) | 0.01 – 0.1 | 0.03 |
| TiType 7 microalloying | 0.01 – 0.1 | 0.03 |
| Nfor V-N strengthening variants | ≤ 0.02 | 0.01 |
| Fe | balance | — |
A656 Grade 80-QT — frequently asked
What is A656 Grade 80-QT used for?
A656 Grade 80-QT is typically used for truck frames, crane booms and mobile equipment structural members. In short: formable 80 ksi plate; weight-critical HSLA structure; stronger than A572-50.
What is the yield strength of A656 Grade 80-QT?
A656 Grade 80-QT has a typical yield strength of 630 MPa (91.4 ksi) and a tensile strength of 720 MPa (104 ksi) — stronger than 79% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is A656 Grade 80-QT easy to machine?
Not especially — machinability is rated fair (44/100, worse than 71% of steel grades). Machines like a 550 MPa HSLA steel — rigid setups, sharp carbide tooling, moderate speeds; plasma/laser cut edges should be dressed before drilling to avoid hard cut-edge layers.
Can A656 Grade 80-QT be welded?
Yes — weldability is rated very good (70/100). Readily weldable with low-hydrogen SMAW/FCAW/GMAW (E80/E81 class consumables); control heat input and preheat thicker plate to limit HAZ softening and hydrogen cracking.
What surface finishes work on A656 Grade 80-QT?
Not anodizable — blast off mill scale then paint, zinc-rich prime, powder coat or hot-dip galvanize; galvanizing bath temperature can slightly relax as-rolled strength.
Can A656 Grade 80-QT be formed, bent or molded?
Cold formable with generous bend radii (typically 2–3 t transverse); bend across the rolling direction and allow for high springback compared with mild steel.
What is the maximum service temperature of A656 Grade 80-QT?
A656 Grade 80-QT is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A656 Grade 80-HR and A656 Grade 80-QT?
HR is the default condition — standard stocked condition: hot-rolled, microalloy-strengthened plate meeting 550 MPa yield with good cold bending. QT: ordered for thick sections where as-rolled processing cannot reach 550 MPa yield, or when maximum toughness at 80 ksi is needed. Yield strength is 590 MPa in HR versus 630 MPa in QT.
Sources
- ASTM A656/A656M — Hot-Rolled Structural Steel, HSLA Plate with Improved Formability — ASTM International (2018)
- ASTM A370 — Mechanical Testing of Steel Products (hardness conversions) — ASTM International (2022)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
- High-strength structural plate datasheets (A656 Gr 80 / Domex-type) — Nucor / SSAB (2023)
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.