Steel A517 Grade B-QT (Quenched and tempered)
Heat-treated state · default condition
ASTM A517 Grade B
Standard as-supplied condition for pressure vessel and high-strength structural plate up to 65 mm thick.
Values for the QT condition
Other A517 Grade B tempers and conditions
A517 Grade B is listed in 3 conditions; see the grade overview at A517 Grade B.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Q&T heavy section | Choose for thick-wall vessels and heavy structures; reduced strength minima reflect lower quench severity through thickness. | 690 | 800 | 18 | 22 HRC | — |
Q&T + PWHT/stress relieved | Required when the fabricated vessel must be post-weld heat treated; expect a modest loss of yield and tensile strength. | 710 | 815 | 19 | 22 HRC | 7.2 % IACS |
QTDefaultThis page Quenched and tempered | Standard as-supplied condition for pressure vessel and high-strength structural plate up to 65 mm thick. | 760 | 860 | 18 | 24 HRC | — |
What is A517 Grade B-QT?
A517 Grade B-QT is A517 Grade B heat treated to QT — standard as-supplied condition for pressure vessel and high-strength structural plate up to 65 mm thick. A517 Grade B-QT has a yield strength of 760 MPa (110 ksi) and a tensile strength of 860 MPa (125 ksi) — stronger than 85% of steel grades. Elongation at break is 18% and the elastic modulus is 205 GPa (29.7 Msi). A517 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 — 130 MPa·√m (118.3 ksi·√in), better than 89% of steel grades
- High strength — 760 MPa (110 ksi), better than 85% of steel grades
Limitations
- Difficult to machine — 38/100, worse than 80% of steel grades
A517 Grade B-QT properties
Typical room-temperature values for A517 Grade B-QT; 13 are specific to this condition. Other listed values are A517 Grade B reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
A517 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
A517 Grade B-QT has a yield strength of 760 MPa (110 ksi) and a tensile strength of 860 MPa (125 ksi) — stronger than 85% of steel grades. Elongation at break is 18% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
A517 Grade B-QT is rated for continuous service to 370°C (698 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical2
A517 Grade B-QT has an electrical resistivity of 2.4×10⁻⁷ Ω·m.
Chemical & Environmental3
Corrosion resistance is not recommended (13/100), better than 66% of steel grades.
Sustainability4
Producing a kilogram of A517 Grade B-QT takes about 30 MJ of energy and emits 2.3 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 25%.
Manufacturability7
A517 Grade B-QT's machinability is fair (38/100, worse than 80% of steel grades); weldability good (55/100); formability fair (40/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A517 Grade B-QT
Is A517 Grade B easy to machine?
Machines like a 250 HB Q&T alloy steel — rigid setups, carbide tooling, moderate speeds; avoid heavy grinding burn that re-hardens the surface.
Can A517 Grade B be welded?
Weld with low-hydrogen 100 ksi-class consumables (E11018-M / ER110S-1), preheat typically 65–150 °C by thickness, and cap heat input to protect the HAZ toughness.
Can A517 Grade B be formed, bent or molded?
Cold bend only at generous radii (≈3–4t or more) with the bend line across the rolling direction; hot forming above the tempering temperature destroys the Q&T properties and requires re-heat-treatment.
What surface finishes work on A517 Grade B?
Not anodizable — protect by shot-blast plus epoxy/zinc-rich paint or metallizing; use caution with hot-dip galvanizing on high-strength plate due to embrittlement risk.
A517 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 | 0.15 – 0.21 | 0.18 |
| 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 |
| V | 0.03 – 0.08 | 0.05 |
| Tigrain refinement / boron protection | 0.01 – 0.03 | 0.02 |
| Bhardenability booster | 5×10⁻⁴ – 0.01 | 0 |
| Fe | balance | — |
A517 Grade B-QT — frequently asked
What is A517 Grade B-QT used for?
A517 Grade B-QT is typically used for pressure vessels, boiler drums and heavy pipe fittings. In short: pressure-vessel T-1 plate; 100 ksi yield vessel steel; cr-Mo-B quenched plate.
What is the yield strength of A517 Grade B-QT?
A517 Grade B-QT has a typical yield strength of 760 MPa (110 ksi) and a tensile strength of 860 MPa (125 ksi) — stronger than 85% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is A517 Grade B-QT easy to machine?
Not especially — machinability is rated fair (38/100, worse than 80% of steel grades). Machines like a 250 HB Q&T alloy steel — rigid setups, carbide tooling, moderate speeds; avoid heavy grinding burn that re-hardens the surface.
Can A517 Grade B-QT be welded?
Yes — weldability is rated good (55/100). Weld with low-hydrogen 100 ksi-class consumables (E11018-M / ER110S-1), preheat typically 65–150 °C by thickness, and cap heat input to protect the HAZ toughness.
What surface finishes work on A517 Grade B-QT?
Not anodizable — protect by shot-blast plus epoxy/zinc-rich paint or metallizing; use caution with hot-dip galvanizing on high-strength plate due to embrittlement risk.
Can A517 Grade B-QT be formed, bent or molded?
Cold bend only at generous radii (≈3–4t or more) with the bend line across the rolling direction; hot forming above the tempering temperature destroys the Q&T properties and requires re-heat-treatment.
What is the maximum service temperature of A517 Grade B-QT?
A517 Grade B-QT is rated for continuous use to about 370°C (698 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A517 Grade B-QT and A517 Grade B QT-HS?
QT is the default condition — standard as-supplied condition for pressure vessel and high-strength structural plate up to 65 mm thick. QT-HS: choose for thick-wall vessels and heavy structures; reduced strength minima reflect lower quench severity through thickness. Yield strength is 760 MPa in QT versus 690 MPa in QT-HS.
Sources
- ASTM A517/A517M — Pressure Vessel Plates, Alloy Steel, High-Strength, Quenched and Tempered — ASTM International (2023)
- ASTM A514/A514M — High-Yield-Strength, Quenched and Tempered Alloy Steel Plate — ASTM International (2023)
- ASME BPVC Section II Part D — Material Properties — ASME (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)
- Constructional alloy plate (T-1 type A/B) technical bulletin — steel plate producer (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.