Constructional Material Heat Resistance Corten a A709 / S355J0W Corten Steel Plate

A709 / S355J0W is a high-strength structural carbon steel plate with enhanced atmospheric corrosion resistance (weathering behavior). It is commonly used for bridge components, heavy structural members, containers, and other outdoor fabrications where long-term durability, aesthetics, and low maintenance are required.

In short: choose A709 Grade 50W / S355J0W when you need a minimum 355 MPa yield strength plate with full traceability, weldability, and a naturally forming rust patina that reduces the need for painting in outdoor applications.

ASTM A709: An American specification developed for structural steels used in bridges, with grades 36, 50, 50W, and HPS types. The "50W" (or S355J0W) indicates a weathering variant with yield strength near 345–355 MPa.

S355J0W: European equivalent designation for weathering S355 grade. J0 = 0 °C impact test, W = weathering.

These plates combine high strength with alloying elements (Cu, Cr, Ni, sometimes P) that promote a protective oxide layer (patina), lowering maintenance costs.

ASTM A709 / A709M – American standard for bridge structural steels. Defines chemical limits, mechanical tests, and inspection criteria.

EN 10025-5 / EN 10155 – European standard for atmospheric corrosion-resistant steels; S355J0W is classified here.

Cross-reference equivalence – A709-50W ≈ S355J0W; always confirm with mill certificates.

Source: Consolidated EN 10025-5 / EN 10155 ranges and supplier mill certificates. Confirm exact composition with each heat certificate.

Mechanical behavior depends on thickness, production method (TMCP, normalized, AR), and heat treatment.

Delivery conditions: +AR (as rolled), +N (normalized), +TMCP / +M (thermo-mechanical control process), or normalized & tempered.

The copper, chromium, and phosphorus content promotes a compact, adherent patina that slows further corrosion.

Best suited for cyclical wet/dry environments (bridges, towers, façades).

Not recommended for continuously submerged service or high-chloride zones without testing.

Proper detailing for fasteners and welds is critical to maintain patina protection.

Weldable via SMAW, GMAW, FCAW.

Preheat and interpass selection per thickness and carbon equivalent.

Control HAZ for plates >20–25 mm to maintain toughness.

Surface preparation should preserve the patina for aesthetic finishes.

Typical forming follows standard S355 procedures; thick plates require adequate tooling.

Bridge girders, stringers, stiffeners (A709 designated)

Outdoor structural components (towers, pedestrian bridges, architectural façades)

Storage tanks and containers exposed to atmosphere

Railway components and heavy equipment frames

Reduced maintenance and long-term durability projects

Weight (kg) = Length (m) × Width (m) × Thickness (mm) × 7.85 ÷ 1,000

Example:

12,000 × 2,000 × 20 mm → 3,768 kg ≈ 3.77 t

6,000 × 1,500 × 10 mm → 707 kg

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What is A709 grade 50W steel?

ASTM A709-50W is a standard specification for structural steel primarily in the fabrication of steel bridges. ASTM A709-50W covers high strength, low allow steel structural shapes, plates and bars.

What is ASTM A709 steel grade?

The ASTM A709 is the Standard Specification for Structural Steel for Bridges and encompasses carbon, high-strength low-alloy, and quenched and tempered alloy steels used as structural plates in the construction of bridges. SSAB offers the following five grades of A709; 36, 50, 50W, HPS 50W and HPS 70W.

What is the difference between ASTM A572 Grade 50 and ASTM A709 Grade 50?

A572 Grade 50: Used in a wide range of structural applications, including buildings, transmission towers, equipment, and general construction. It's not specifically optimized for bridges. A709 Grade 50: Primarily used for bridge construction and other structures where enhanced toughness and weldability are critical.

What is the yield strength of ASTM A709 grade 50?

Grade 50 steel of this specification requires a minimum yield strength of 50 ksi. Used as structural members in bridge building or for similar structures.

What is the difference between ASTM A36 and A709?

ASTM A709 grade 36 is a bridge material wherein carbon adds to the strength and hardenability of the steel. A36 has less than0. 30% carbon and thus, do not possess high hardenability. ASTM A709 grade 36 steel plate has improved corrosion resistance and can be used in outdoor applications.

What is ASTM A572 grade 50 equivalent to?

ASTM A572 Grade 50 is equivalent to several other steel grades, with the most common international equivalents being S355JR (European standard) and Q345B (Chinese standard). The best equivalent depends on the specific project requirements, so it is always best to consult material specifications and a specialist to confirm compatibility.

What is the difference between ASTM A36 and ASTM A572 GR 50?

As mentioned earlier, A36 is steel that has a minimum yield strength of 36,000 PSI. This grade derives its strength from a combination of carbon and manganese. On the other hand, A572-50, for example, is a type of steel with a minimum yield strength of 50,000 PSI.

What is the difference between A572 and s355?

In summary, both ASTM A572 Grade 50 and S355JR are excellent choices for structural steel applications, with ASTM A572 Grade 50 providing higher strength capabilities and S355JR offering versatility and widespread use in European construction projects.

Is A572 steel corrosion resistant?

A572 steel is typically used in structural applications due to its high strength, ductility, weldability and corrosion resistance. These applications include structural sections, reinforcing bars, bridges, skyscrapers and houses.