S355K2W is an improved weathering structural steel that complies with the European standard EN 10025-5 for atmospheric corrosion-resistant structural steel. It is also known as weathering steel or Corten steel. Compared to other grades of weathering steel in the S355W series, it offers higher impact energy at -20°C (≥40 J).

It resists atmospheric corrosion by forming a protective rust layer on its own. This makes it particularly suitable for outdoor structural engineering in cold climates, where low maintenance costs, long service life, and specific aesthetic effects are desired. It is commonly used in buildings, bridges, railway vehicles, containers, and other structures that are exposed to the atmosphere for extended periods.

By adding alloying elements such as copper and chromium, S355K2W forms a dense, stable, and strongly adherent oxide layer (patina) in atmospheric environments, effectively preventing further corrosion. Its weather resistance is typically 4 to 6 times that of ordinary carbon steel, especially excelling in industrial, marine, and rural atmospheric environments.

Key Features and Advantages

1. Excellent atmospheric corrosion resistance: The corrosion resistance is 4-6 times that of ordinary carbon steel, depending on the environment (rural, urban, industrial, marine).

2. Better mechanical properties: Yield strength ≥355 MPa, tensile strength of 470-630 MPa, and impact energy ≥40 J at -20°C.

3. Weldability: Good welding performance, but specific weathering steel welding procedures must be followed (e.g., using matching weathering electrodes, controlling heat input, etc.) to maintain corrosion resistance in the welded areas.

4. Ease of processing: Can be cut, bent, welded, etc., with good formability.

5. No need for painting and low maintenance costs: Under suitable environments, painting can be omitted or the painting maintenance cycle can be significantly extended, greatly reducing maintenance costs over the entire lifecycle.

6. Environmentally friendly and economical: Reduces pollution related to coatings, extends service life, and offers lower lifecycle costs.

7. Unique industrial aesthetic: Over time, the steel surface develops a distinctive, uniform rust-red or dark brown appearance, which holds industrial aesthetic value.

Carbon Equivalent of S355K2W Weathering Steel Plate (Corten Steel Plate)

Carbon Equivalent: CEV ≤ 0.52%

Calculate using the International Institute of Welding (IIW) formula: CEV = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15

S355K2W Weathering Steel Plate (Corten Steel Plate) is particularly suitable for structural engineering in cold climates where long-term exposure to the atmosphere is required, keeping maintenance difficult or in the pursuit of specific aesthetic effects.

1. Bridges: Especially external structures such as trusses and box girders of railway bridges and highway bridges.

2. Exposed architectural structures: Supporting structures for building curtain walls, roof trusses of stadiums, and steel frameworks of exhibition centers and art galleries.

3. Tower structures: Transmission towers, communication towers, and lighthouses.

4. Sculptures and art installations: Utilizing the aesthetic effect of natural rusting.

5. Shipping containers and cargo equipment.

Usage Precautions

1. Environmental Suitability: The weather resistance performs well in rural, urban, or industrial atmospheric environments. However, in continuously humid, salt spray (coastal), highly chemically polluted, or long-term immersion environments, the protective rust layer may not form stably or may be damaged, which will accelerate corrosion rates. In such cases, additional protective measures may be required.

2. “Runoff Rust Water” Phenomenon: During the initial stabilization period of the rust layer (which typically takes several years), rainwater may wash away iron-containing runoff water, potentially staining surrounding walls or ground. Drainage design or initial diversion measures should be considered.

3. Welding and Processing: The material exhibits good weldability, but the welding materials (electrodes, wires) should be compatible with it. Weathering steel-specific welding materials are typically recommended to maintain corrosion resistance in the weld area. After processing (cutting, drilling), the exposed fresh metal edges may have slightly reduced corrosion resistance.

4. Contact with Other Materials: Direct contact with less active metals, such as stainless steel or copper, should be avoided to prevent galvanic corrosion. Additionally, prolonged contact with ordinary carbon steel should be avoided, as corrosion products from carbon steel may contaminate and affect the protective rust layer.

Key Differences Between Similar Grades

International Standard Equivalence

* Since the requirements for chemical composition, mechanical properties, and corrosion resistance mechanisms vary slightly across different standards, "equivalence" typically refers to similarities in intended use and performance rather than exact identity.