Steel A299 GrB-N
Heat-treated state
ASTM A299
GrB-N = grade B, normalized
Grade B in heavy sections or where toughness and through-thickness uniformity matter.
Values for the GrB-N condition
Other A299 tempers and conditions
A299 is listed in 7 conditions; see the grade overview at A299.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Normalized + stress relieved / simulated PWHT | Ordered when plate must be tested in the simulated post-weld-heat-treated condition for code vessels. | 315 | 555 | 25 | 155 HB | 10 % IACS |
GrA-ARDefault Grade A, as-rolled | Default stock condition for A299 Grade A plate up to about 38 mm where no normalizing is specified. | 320 | 560 | 23 | 160 HB | 10 % IACS |
ASTM A299 Grade A | Lower-strength grade of ASTM A299 carbon-manganese-silicon plate for welded boilers and pressure vessels, supplied as-rolled or normalized per thickness. | 320 | 560 | 24 | 160 HB | 49 W/m·K |
Grade A, normalized | Choose for thick plate (>38 mm) or where finer grain and better notch toughness are required. | 330 | 545 | 25 | 155 HB | — |
ASTM A299 Grade B | Higher-strength grade of ASTM A299 Mn-Si plate, same chemistry family as Grade A but tested to a raised tensile/yield band for thicker vessel shells. | 350 | 600 | 22 | 175 HB | 48 W/m·K |
Grade B, as-rolled | Higher-strength grade of A299 for maximum allowable stress / minimum wall thickness in as-rolled plate. | 360 | 600 | 21 | 175 HB | — |
GrB-NThis page Grade B, normalized | Grade B in heavy sections or where toughness and through-thickness uniformity matter. | 370 | 585 | 23 | 170 HB | 10 % IACS |
What is A299 GrB-N?
A299 GrB-N is A299 heat treated to GrB-N — grade B in heavy sections or where toughness and through-thickness uniformity matter. A299 GrB-N has a yield strength of 370 MPa (53.7 ksi) and a tensile strength of 585 MPa (84.8 ksi) — weaker than 70% of steel grades. Elongation at break is 23% and the elastic modulus is 200 GPa (29 Msi). A299 GrB-N 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). GrA-AR is the default condition FabDigit quotes; GrB-N is available on request or by drawing note.
Advantages
- Conducts heat well — 49 W/m·K (28.3 BTU/hr·ft·°F), better than 83% of steel grades
- High electrical conductivity — 10 % IACS, better than 83% of steel grades
Limitations
- Hard to polish — 45/100, worse than 84% of steel grades
A299 GrB-N properties
Typical room-temperature values for A299 GrB-N; 23 are specific to this condition. Other listed values are A299 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
A299 GrB-N 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
A299 GrB-N has a yield strength of 370 MPa (53.7 ksi) and a tensile strength of 585 MPa (84.8 ksi) — weaker than 70% of steel grades. Elongation at break is 23% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
A299 GrB-N is rated for continuous service to 425°C (797 °F). It conducts heat at 49 W/m·K (28.3 BTU/hr·ft·°F), better than 83% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
A299 GrB-N conducts electricity at 10 % IACS, better than 83% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of A299 GrB-N takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 25%.
Manufacturability6
A299 GrB-N's machinability is fair (52/100, better than 52% of steel grades); weldability very good (70/100); formability fair (52/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A299 GrB-N
Is A299 easy to machine?
Machines like medium-carbon C-Mn plate (~60 % of AISI 1212); use rigid setups, carbide tooling and moderate speeds — as-rolled banded structure can give stringy chips.
Can A299 be welded?
Weldable by SMAW/SAW/GMAW with low-hydrogen consumables; carbon equivalent near 0.45 means preheat 100–150 °C on thick plate and PWHT at 595–650 °C for code vessels.
Can A299 be formed, bent or molded?
Hot-form heads and shells at 900–1000 °C followed by re-normalizing; cold rolling of shells is practical with generous bend radii due to the higher yield strength.
What surface finishes work on A299?
No inherent corrosion resistance — shot blast to SA 2.5 and apply epoxy/zinc-rich primer, galvanizing or internal cladding; polishing gives only utility finishes.
A299 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 |
|---|---|---|
| C0.28 max ≤25 mm; increases with thickness (to ~0.30–0.33) | ≤ 0.3 | 0.26 |
| Mn0.90–1.40 for ≤25 mm; 1.15–1.50 for thicker plate | 0.9 – 1.5 | 1.25 |
| Si | 0.15 – 0.4 | 0.25 |
| Pheat analysis max | ≤ 0.04 | 0.02 |
| Sheat analysis max | ≤ 0.04 | 0.01 |
| Febalance, residual Cu/Ni/Cr/Mo per A20 limits | balance | — |
A299 GrB-N — frequently asked
What is A299 GrB-N used for?
A299 GrB-N is typically used for pressure vessels, boiler shells and storage tanks. In short: stronger than A285/A515; weldable C-Mn vessel plate; 425 °C service limit.
What is the yield strength of A299 GrB-N?
A299 GrB-N has a typical yield strength of 370 MPa (53.7 ksi) and a tensile strength of 585 MPa (84.8 ksi) — weaker than 70% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is A299 GrB-N easy to machine?
Reasonably — machinability is rated fair (52/100, better than 52% of steel grades). Machines like medium-carbon C-Mn plate (~60 % of AISI 1212); use rigid setups, carbide tooling and moderate speeds — as-rolled banded structure can give stringy chips.
Can A299 GrB-N be welded?
Yes — weldability is rated very good (70/100). Weldable by SMAW/SAW/GMAW with low-hydrogen consumables; carbon equivalent near 0.45 means preheat 100–150 °C on thick plate and PWHT at 595–650 °C for code vessels.
What surface finishes work on A299 GrB-N?
No inherent corrosion resistance — shot blast to SA 2.5 and apply epoxy/zinc-rich primer, galvanizing or internal cladding; polishing gives only utility finishes.
Can A299 GrB-N be formed, bent or molded?
Hot-form heads and shells at 900–1000 °C followed by re-normalizing; cold rolling of shells is practical with generous bend radii due to the higher yield strength.
What is the maximum service temperature of A299 GrB-N?
A299 GrB-N is rated for continuous use to about 425°C (797 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A299 GrA-AR and A299 GrB-N?
GrA-AR is the default condition — default stock condition for A299 Grade A plate up to about 38 mm where no normalizing is specified. GrB-N: grade B in heavy sections or where toughness and through-thickness uniformity matter. Yield strength is 320 MPa in GrA-AR versus 370 MPa in GrB-N.
Sources
- ASTM A299/A299M — Pressure Vessel Plates, Carbon Steel, Manganese-Silicon — ASTM International (2020)
- ASTM A20/A20M — General Requirements for Steel Plates for Pressure Vessels — ASTM International (2020)
- ASME BPVC Section II Part D — Properties (Metric) — ASME (2023)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
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.