If you are uncertain which grade best matches your drawing requirements or site‑service conditions, please send your project parameters to our technical team. GNEE Steel will provide grade‑selection recommendations free of charge.
ASTM A588 Grade A Grade B High Strength Low Alloy Corten Steel Plate Specification
| Item | ASTM A588 Grade A Grade B High Strength Low Alloy Corten Steel Plate |
| Standard&Grade | ASTM A588 Grade A Grade B |
| Thickness |
1.0-1.5mm for cold sheet scope; 1.6-40mm for hot rolled plate |
| Width&Length | 1000mm/1175mm/1220mm/1500mm/1800mm/2000mm |
| Length from cutting, as requirement | |
| Surface | Mill surface Or Rusted finish |
| Package | Standard export package with metal pallet + angle bar protection + |
| Processing | Edging/Laser(Plasma/Water Jet) cutting/Leveling/Slitting |
ASTM A588 Gr.A vs Gr.B Low Alloy Steel Plate: Mechanical Property
| Grade | Thickness | Yield Strength ReH[N/mm2]transv.min |
TensileStrength Rm[N/mm2]transv |
| ASTM A588 | 0mm-100mm | 345 MPa | 480 MPa |
| 102mm-127mm | 320 MPa | 460 MPa | |
| 127mm-203mm | 290 MPa | 430 MPa |
ASTM A588 Gr.A vs Gr.B Low Alloy Steel Plate: Chemical Composition
| Grade | C % | Si % | Mn % | P % | S % | Cr % | V % | Ni % | Cu % |
| A588 Gr A | 0.19 | 0.30-0.65 | 0.80-1.25 | 0.04 | 0.05 | 0.40-0.65 | 0.02-0.10 | 0.40 | 0.25-0.5 |
| A588 Gr B | ≤0.20 | 0.15-0.50 | 0.75-1.35 | 0.040 | 0.050 | 0.40-0.70 | 0.01-0.10 | ≤0.50 | ≤0.50 |
ASTM A588 Gr.A vs Gr.B Steel Plate: Weather‑Resisting Performance
Both grades rely on the Cu‑Cr‑Ni alloy system to develop a dense protective patina. They deliver comparable baseline atmospheric corrosion resistance in clean rural atmospheric environments.
ASTM A588 Grade A
Its higher minimum copper content guarantees stable patina formation under rural and general urban atmospheric conditions. It produces a consistent, aesthetically favourable weathered appearance for building facades and art installations.
ASTM A588 Grade B
It permits higher upper limits for chromium and nickel contents. It offers marginally superior patina stability in industrially polluted atmospheres and mild coastal splash zones. Nevertheless, uncoated Grade B cannot fully resist corrosion under heavy salt‑spray marine conditions.
Note: No standardised test data demonstrates substantially better corrosion resistance for Grade B. The difference between the two grades is incremental rather than fundamental. The protective patina of both grades will degrade upon prolonged immersion in salt‑water.
ASTM A588 Gr.A vs Gr.B High Strength Steel Plate: Manufacturing and Fabrication Properties
Weldability
ASTM A588 Grade A
Higher silicon content promotes improved weld bead profile with fewer surface defects and lower risk of heat‑affected zone (HAZ) embrittlement. It is the preferred option for complex multi‑pass welding of medium‑thin plates, building curtain walls and sculptural components. Preheat requirements are relatively lenient for plate thicknesses below 32 mm.
ASTM A588 Grade B
Lower silicon content yields acceptable weld appearance, yet inferior smoothness for decorative welds. Carbon Equivalent (CEQ) varies with manganese content. Preheating is recommended for plates thicker than 40 mm to prevent cold cracking.
Low‑Temperature Toughness
ASTM A588 Grade A
Satisfies service requirements for general ambient‑temperature structures; however, it provides limited safety margin under heavy‑load conditions at sub‑zero temperatures.
ASTM A588 Grade B
Benefiting from higher maximum nickel content and broader manganese range, it exhibits enhanced low‑temperature Charpy toughness and is better suited for heavy‑duty structures subjected to cyclic loading in cold northern regions.
Cold Forming and Bending
ASTM A588 Grade A
Narrow alloy composition range yields consistent Carbon Equivalent (CEQ). It performs better in intricate cold bending, punching and artistic cutting operations with reduced cracking risk for complex profiles.
ASTM A588 Grade B
Good cold‑forming capability; larger bend radii shall be adopted for heavy‑gauge plates.
GNEE Steel provides pre‑patination surface treatment, laser cutting, bending and drilling services for both A588 Gr.A and Gr.B. Please submit your DXF drawings for processing quotations.
ASTM A588 Gr.A vs Gr.B Weathering Steel Plate: Cost Comparison
Raw‑material cost: For identical dimensions, ASTM A588 Grade B carries a price premium of approximately 3%‑7% over Grade A. This cost difference originates from tighter metallurgical control over manganese ranges as well as chromium and nickel contents during steelmaking.
Fabrication cost:
Grade A: Suited for building projects with extensive welding and complex bending operations, featuring lower fabrication costs and fewer preheat operations during site erection.
Grade B: For heavy‑plate projects, additional preheat requirements for welding may raise on‑site labour expenses.
Overall project economy:
Light‑load building curtain‑wall projects: Grade A delivers superior overall cost‑effectiveness.
Heavy‑duty bridges, cold‑climate and coastal‑industrial projects: Despite marginally higher material cost for Grade B, its additional long‑term structural safety margin offsets this price difference.
ASTM A588 Gr.A vs Gr.B Weathering Steel Plate: Typical Application Scenarios
When to select ASTM A588 Grade A
- Weathering‑steel curtain‑wall panels, landscape sculptures and decorative screens
- Light‑duty pedestrian bridges and park structures
- Solar mounting supports and lightweight outdoor steel structures
- Projects involving extensive site welding and complex cold‑forming processes
When to select ASTM A588 Grade B
- Main girders for highway and railway steel bridges, heavy‑duty trusses
- Power‑transmission towers, communication towers and main frames for freight railcars
- Outdoor load‑bearing structures in cold northern regions
- Heavy steel components for industrial zones and mild coastal atmospheric environments
Services Available from GNEE Steel
Quality Assurance: Each shipment is supplied with EN 10204 3.1 Material Test Certificates (MTC), offering full traceability for chemical and mechanical‑property data. Ultrasonic Testing (UT), Z‑direction property testing and third‑party inspection by SGS / BV are available upon customer request. Dimensional tolerances strictly comply with ASTM A6.
Secondary Processing Services: Laser / plasma cutting, bending, drilling, blasting and pre‑patination (artificial rust finish). Fabrication can be performed according to customer‑supplied DXF / DWG drawings.
Feel free to request free samples or the latest FOB quotation. Kindly advise your required thickness, quantity and service environment, and our export engineers will respond within 24 working hours.
FAQ
Is A588 Grade B stronger than Grade A?
No, ASTM A588 Grade B is not structurally stronger than Grade A. Both grades share the exact same baseline mechanical strength requirements, featuring a minimum yield strength of 50 ksi (345 MPa) and a minimum tensile strength of 70 ksi (485 MPa) for standard thicknesses.
Which grade suits coastal bridge construction, A588 Grade A or Grade B?
Both ASTM A588 Grade A and Grade B share identical atmospheric corrosion resistance and the same minimum yield strength (345 MPa / 50 ksi). Selection depends on material thickness and structural load rather than coastal exposure: Grade A fits thinner structural shapes/plates (≤ 16 mm), while Grade B is designated for thicker heavy-duty sections (> 16 mm).
What are equivalent grades of A588 Grade A & B?
ASTM A588 Grade A and Grade B are high-strength low-alloy structural weathering steels with a 50 ksi minimum yield strength. International equivalents include European [EN 10025-5] grades like S355J2W and S355K2G1W, Chinese Q355NH, Japanese SPA-H (for thinner sections), and domestic equivalents like ASTM A242.
What pre‑heat temperature should I adopt for welding A588 steel?
For ASTM A588 weathering steel, the required pre-heat temperature generally ranges from 50°F to 225°F (10°C to 107°C). The exact minimum temperature depends heavily on the thickness of the steel plate and the ambient temperature at the time of welding.
