A588 Grade A corten steel structure
A588GrA corten steel sheet metal is the American Standard weathering steel plate, also is the implementation of ASTMA 588/A588M-05 in a kind of high-strength low alloy steel resistant to atmospheric corrosion.
A588GrA corten sheet Delivery condition: hot rolled, tempered, normalised + tempered, tempered. If you have special needs, we can choose the delivery method according to your requirements.
Application of A588GrA weathering steel sheet: widely used in various weathering-resistant building structural parts (especially for industrial atmospheric environment), bridge auxiliary structural parts and so on.
weathering plate Chemical Composition
| C | Mn | P | S | SI | Ni | Cr | Mo | Cu | V | Nb |
| ≤0.19 | 0.8-1.25 | ≤0.04 | ≤0.05 | 0.3-0.65 | ≤0.04 | 0.4-0.65 | ~ | 0.25-0.5 | 0.02-0.1 | ~ |
corten steel mechanical property
| Yield Strength Mpa | Tensile Strength Mpa | Elongation % in 200mm | Elongation % in 50mm | Thickness | ||||||
| ≥345 | ≥485 | 18 | 21 | less 100mm | ||||||
| ≥315 | ≥460 | 100-125mm | ||||||||
| ≥290 | ≥435 | 125-200mm | ||||||||
What is A588 steel equivalent to?
Corten A steel plate
The ASTM A588 grade A plate is equivalent to Corten A steel plate. ASTM A242 plate is equivalent to Corten B.
What is ASTM A588 used for?
ASTM A588, in particular, is intended for use in applications where savings in weight, added durability and extended life cycle are paramount, such as welded bridges and buildings. ASTM A588 is commonly used to construct pedestrian bridges, highway bridge girders, ships, tanks, railcars, fencing and sculptures.
Is ASTM A588 Grade A or B?
When comparing ASTM A588 Grade A and ASTM A588 Grade B, it is important to understand that they are "sibling" grades. They share the same structural DNA and the same "Corten" aesthetic, but they differ slightly in their chemical recipes and thickness capabilities.
For most architectural and landscape projects, they are virtually interchangeable. However, for heavy structural engineering (like bridges), the differences become critical.
When comparing ASTM A588 Grade A and ASTM A588 Grade B, it is important to understand that they are "sibling" grades. They share the same structural DNA and the same "Corten" aesthetic, but they differ slightly in their chemical recipes and thickness capabilities.
For most architectural and landscape projects, they are virtually interchangeable. However, for heavy structural engineering (like bridges), the differences become critical.
1. Comparison of Chemical Composition (The "DNA")
The primary difference lies in the alloying elements used to create the protective "patina" (rust layer).
| Element | A588 Grade A (%) | A588 Grade B (%) | Technical Impact |
| Silicon (Si) | 0.30 – 0.65 | 0.15 – 0.50 | Grade A has higher Silicon, often resulting in a slightly different initial oxidation texture. |
| Chromium (Cr) | 0.40 – 0.65 | 0.40 – 0.70 | Grade B allows for higher Chromium, enhancing deep-section corrosion resistance. |
| Nickel (Ni) | ≤ 0.40 | ≤ 0.50 | Grade B has a higher Nickel ceiling, improving toughness in thicker plates. |
| Copper (Cu) | 0.25 – 0.40 | 0.20 – 0.40 | Both use Copper as the primary driver for the "self-healing" rust layer. |
| Vanadium (V) | 0.02 – 0.10 | 0.01 – 0.10 | Both use Vanadium for grain refinement and strength. |
2. Thickness & Structural Limits
This is the most significant difference for structural engineers:
ASTM A588 Grade A: The yield strength of 50 ksi (345 MPa) is guaranteed for thicknesses up to 4 inches (100 mm). It is the "standard" for most medium-duty structural work.
ASTM A588 Grade B: This grade is optimized for heavier sections. It maintains its 50 ksi (345 MPa) yield strength for thicknesses up to 8 inches (200 mm).
Purchaser Insight: If your project requires massive, load-bearing plates (over 4 inches thick), you must specify Grade B. For thinner architectural panels (3mm–20mm), Grade A is the market standard.
3. Mechanical Properties (Identical)
Despite the chemical differences, their "muscle" is the same for standard thicknesses:
Yield Strength:≥50 ksi (345 MPa)
Tensile Strength:≥70 ksi (485 MPa)
Elongation:≥21% (in 2 inches)
Corrosion Index (ASTM G101): Both must meet an I-value ≥6.0.
This ensures that both will last 50+ years without painting in normal atmospheric conditions.
4. What do Purchasers care about? (Addressing Common Doubts)
■ "Will they look different?"
No. Once fully weathered (after 18–24 months), Grade A and Grade B develop the same deep chocolate-brown patina. Neither an architect nor a client will be able to tell the difference visually.
■ "Is one easier to weld than the other?"
Practically, no. Both are High-Strength Low-Alloy (HSLA) steels. As long as you use weathering-grade welding consumables (e.g., E8018-W2 electrodes or ER80S-Ni1 wires), both grades weld beautifully. The low carbon content (≤0.19/0.20%) ensures excellent weldability.
■ "Which one is more available?"
Grade A is the "King of Stock." Most steel service centers keep Grade A in their inventory because it covers the vast majority of architectural and light-bridge requirements. Grade B is frequently a "Mill Order" item unless you are dealing with a specialized heavy-plate supplier.
"Confused between A588 Grade A and Grade B for your next project?"
Architectural Projects: We recommend ASTM A588 Grade A for its high availability and perfect surface finish for facades, planters, and screens.
Heavy Infrastructure: We supply ASTM A588 Grade B for heavy structural sections up to 200mm, ensuring your bridge or skyscraper meets the highest safety codes.
Our Value-Add: Whether you choose Grade A or B, we provide Professional Pre-Rusting to give you an instant patina and Rust-Fixing Sealants to prevent staining on your concrete foundations.
[Get a Quote & MTC Sample Today]
Summary for your customers:
Choose Grade A for standard construction, architectural facades, and landscape features under 4" thick.
Choose Grade B for heavy structural plates, bridges, and components between 4" and 8" thick.
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