Steel A514 Grade B-QT (Quenched and tempered)
Heat-treated state · default condition
ASTM A514 Grade B
Standard as-rolled-and-Q&T mill condition for plate up to 65 mm — the normal stock item for T-1 fabrication.
Values for the QT condition
Other A514 Grade B tempers and conditions
A514 Grade B is listed in 4 conditions; see the grade overview at A514 Grade B.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
over 65 mm to 150 mm (2.5–6 in), 620 MPa min yield | Choose for thick sections; ASTM allows a lower yield/tensile band because of reduced quench severity through thickness. | 690 | 780 | 18 | 22 HRC | — |
Q&T + stress relieved | Used after heavy welding or machining of thick weldments where dimensional stability matters; accept a small strength/toughness trade-off. | 720 | 790 | 20 | 23 HRC | 8 % IACS |
QTDefaultThis page Quenched and tempered | Standard as-rolled-and-Q&T mill condition for plate up to 65 mm — the normal stock item for T-1 fabrication. | 760 | 820 | 19 | 25 HRC | — |
Q&T with supplementary Charpy V-notch testing | Order this when the code or bridge/crane spec requires documented low-temperature notch toughness. | 760 | 820 | 20 | 24 HRC | 8 % IACS |
What is A514 Grade B-QT?
A514 Grade B-QT is A514 Grade B heat treated to QT — standard as-rolled-and-Q&T mill condition for plate up to 65 mm — the normal stock item for T-1 fabrication. A514 Grade B-QT has a yield strength of 760 MPa (110 ksi) and a tensile strength of 820 MPa (119 ksi) — stronger than 85% of steel grades. Elongation at break is 19% and the elastic modulus is 205 GPa (29.7 Msi). A514 Grade B-QT has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Advantages
- Tough — resists crack growth — 140 MPa·√m (127.4 ksi·√in), better than 94% of steel grades
- High strength — 760 MPa (110 ksi), better than 85% of steel grades
Limitations
- Difficult to machine — 35/100, worse than 84% of steel grades
A514 Grade B-QT properties
Typical room-temperature values for A514 Grade B-QT; 14 are specific to this condition. Other listed values are A514 Grade B reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
A514 Grade B-QT has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
A514 Grade B-QT has a yield strength of 760 MPa (110 ksi) and a tensile strength of 820 MPa (119 ksi) — stronger than 85% of steel grades. Elongation at break is 19% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
A514 Grade B-QT is rated for continuous service to 400°C (752 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 11.7 µm/m·K (6.5 µin/in·°F).
Electrical3
A514 Grade B-QT conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (15/100), better than 75% of steel grades.
Sustainability4
Producing a kilogram of A514 Grade B-QT takes about 31 MJ of energy and emits 2.3 kg of CO₂ — more than 64% of steel grades. Typical recycled content is 30%.
Manufacturability7
A514 Grade B-QT's machinability is fair (35/100, worse than 84% of steel grades); weldability good (60/100); formability fair (35/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A514 Grade B-QT
Is A514 Grade B easy to machine?
Machine at roughly 30 % of 1212 rates with rigid setups, carbide tooling and generous coolant; drill and tap slowly — the Q&T structure work-hardens and dulls HSS quickly.
Can A514 Grade B be welded?
Weldable with low-hydrogen SMAW/FCAW/SAW consumables matching ~690 MPa; use moderate preheat (typically 50–150 °C by thickness), strictly limit heat input and interpass temperature, and never exceed the mill tempering temperature.
Can A514 Grade B be formed, bent or molded?
Cold-form only, with bend radii of about 3–4 t and press-brake allowance for high springback; hot forming above ~600 °C destroys the quench-and-temper properties and requires re-heat-treatment.
What surface finishes work on A514 Grade B?
No anodizing; protect with blast-and-paint systems, thermal-spray zinc or metallizing. Avoid unbaked electroplating and aggressive acid pickling because of hydrogen-embrittlement risk at this strength level.
A514 Grade B 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 | 0.12 – 0.21 | 0.17 |
| Mn | 0.7 – 1 | 0.85 |
| Si | 0.2 – 0.35 | 0.28 |
| P | ≤ 0.04 | — |
| S | ≤ 0.04 | — |
| Cr | 0.4 – 0.65 | 0.52 |
| Mo | 0.15 – 0.25 | 0.2 |
| Tiprotects boron effectiveness | 0.01 – 0.1 | 0.04 |
| V | 0.03 – 0.08 | 0.05 |
| Bhardenability booster | 5×10⁻⁴ – 0.01 | 0 |
| Fe | balance | — |
A514 Grade B-QT — frequently asked
What is A514 Grade B-QT used for?
A514 Grade B-QT is typically used for mobile crane booms, heavy equipment frames, structural weldments and bridge components. In short: classic 100 ksi T-1 plate; weldable high-strength plate; heavy-fabrication standard.
What is the yield strength of A514 Grade B-QT?
A514 Grade B-QT has a typical yield strength of 760 MPa (110 ksi) and a tensile strength of 820 MPa (119 ksi) — stronger than 85% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is A514 Grade B-QT easy to machine?
Not especially — machinability is rated fair (35/100, worse than 84% of steel grades). Machine at roughly 30 % of 1212 rates with rigid setups, carbide tooling and generous coolant; drill and tap slowly — the Q&T structure work-hardens and dulls HSS quickly.
Can A514 Grade B-QT be welded?
Yes — weldability is rated good (60/100). Weldable with low-hydrogen SMAW/FCAW/SAW consumables matching ~690 MPa; use moderate preheat (typically 50–150 °C by thickness), strictly limit heat input and interpass temperature, and never exceed the mill tempering temperature.
What surface finishes work on A514 Grade B-QT?
No anodizing; protect with blast-and-paint systems, thermal-spray zinc or metallizing. Avoid unbaked electroplating and aggressive acid pickling because of hydrogen-embrittlement risk at this strength level.
Can A514 Grade B-QT be formed, bent or molded?
Cold-form only, with bend radii of about 3–4 t and press-brake allowance for high springback; hot forming above ~600 °C destroys the quench-and-temper properties and requires re-heat-treatment.
What is the maximum service temperature of A514 Grade B-QT?
A514 Grade B-QT 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 A514 Grade B-QT and A514 Grade B QT-SR?
QT is the default condition — standard as-rolled-and-Q&T mill condition for plate up to 65 mm — the normal stock item for T-1 fabrication. QT-SR: used after heavy welding or machining of thick weldments where dimensional stability matters; accept a small strength/toughness trade-off. Yield strength is 760 MPa in QT versus 720 MPa in QT-SR.
Sources
- ASTM A514/A514M — Standard Specification for High-Yield-Strength, Quenched and Tempered Alloy Steel Plate, Suitable for Welding — ASTM International (2018)
- ASTM A517/A517M — Pressure Vessel Plates, Alloy Steel, High-Strength, Quenched and Tempered — ASTM International (2023)
- 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)
- T-1 / high-strength Q&T plate technical and welding data — plate mill producer literature (2020)
- AWS D1.1 Structural Welding Code — Steel (preheat and heat-input guidance for A514) — American Welding Society (2020)
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.