Corten A and Corten B corten steel plates are two widely used grades of weathering steel, also known as atmospheric corrosion-resistant steel.
Corten B corten steel plates
Both grades are designed to form a protective rust layer (patina) that enhances corrosion resistance without the need for painting, making them ideal for bridges, containers, railway vehicles, and outdoor structures.
However, the two grades differ in strength, toughness, alloying elements, and typical applications.
Overview of Corten A and Corten B
| Feature | Corten A | Corten B |
|---|---|---|
| Yield Strength | ~345 MPa | ~355–450 MPa |
| Tensile Strength | 470–580 MPa | 470–630 MPa |
| Impact Toughness | Moderate | High, especially at low temperatures |
| Thickness Availability | Up to 15–20 mm | Up to 25–30 mm |
| Main Alloying Elements | Cu, P, Cr | Cu, Cr, Ni, Mo, Nb, V, Ti |
| Typical Use | Light to medium structural applications | Heavy-duty structural applications |
Corten B has higher strength and toughness than Corten A, making it suitable for heavier structures and thicker plates.
Chemical Composition of Corten A and Corten B
| Element (wt%) | Corten A | Corten B |
|---|---|---|
| Carbon (C) | 0.12–0.18 | 0.12–0.20 |
| Silicon (Si) | 0.20–0.50 | 0.20–0.50 |
| Manganese (Mn) | 0.80–1.25 | 0.80–1.50 |
| Phosphorus (P) | ≤0.07 | ≤0.035 |
| Sulfur (S) | ≤0.035 | ≤0.030 |
| Copper (Cu) | 0.25–0.55 | 0.20–0.50 |
| Chromium (Cr) | 0.50 max | 0.30–0.50 |
| Nickel (Ni) | – | 0.20–0.40 |
| Microalloys (Nb, V, Ti) | Rare | Trace, for strength and toughness |
Corten B contains Ni and additional microalloying elements for improved low-temperature toughness, while Corten A is simpler and more suitable for lighter structures.
Mechanical Properties of Corten A and Corten B Corten Steel
| Property | Corten A | Corten B |
|---|---|---|
| Yield Strength | ≥345 MPa | ≥355–450 MPa |
| Tensile Strength | 470–580 MPa | 470–630 MPa |
| Elongation (A%) | ≥20% | ≥18% |
| Impact Toughness | Moderate | Excellent (-20°C or lower) |
| Hardness (HB) | 140–180 | 150–200 |
Corten B offers higher strength and toughness, particularly for applications requiring low-temperature performance or heavy loading.
Corrosion Resistance of Corten A and Corten B Corten Steel
Both Corten A and B develop a stable rust layer (patina) that protects the steel from atmospheric corrosion.
| Feature | Corten A | Corten B |
|---|---|---|
| Patina Formation | Slower | Faster, denser, more protective |
| Maintenance | Low | Very low; extended lifecycle |
| Outdoor Suitability | Moderate | Excellent, for harsh environments |
For heavily exposed structures or critical load-bearing components, Corten B is preferred due to its faster patina development and superior corrosion resistance.
Typical Applications of Corten A and Corten B Corten Steel
| Application | Corten A | Corten B |
|---|---|---|
| Bridges | Light structural elements | Main girders, deck plates |
| Containers & Railway Cars | Moderate | Heavy-duty frames, chassis |
| Construction Machinery | Small frames | Booms, heavy equipment |
| Architectural & Urban Design | Sculptures, panels | Large façades, urban installations |
| Outdoor Equipment | Moderate | Tanks, platforms, structural members |
While Corten A is suitable for lighter outdoor applications, Corten B is the go-to choice for heavy-duty, low-maintenance structures.
Corten A: Ideal for light to medium-duty outdoor structures with moderate corrosion resistance.
Corten B: Designed for high-strength, low-maintenance heavy-duty structures, offering superior low-temperature toughness and corrosion resistance.
Choose Corten B when long-term durability, low maintenance, and high structural performance are priorities, particularly in bridges, railway cars, containers, and large-scale architectural projects.
Investing in Corten B ensures structural reliability, extended service life, and reduced lifecycle costs compared to Corten A.
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What is the equivalent of Corten B steel?
Corten A has added phosphorous, which makes it suitable for aesthetic facias and gas flue applications, while Corten B is better suited for heavy and load-bearing structures. S355JOW is an equivalent weathering steel to Corten B.
What is Corten used for?
CORTEN steel has atmospheric corrosion resistance and this enables it to be used without paint for many structural / architectural applications, which include structures like bridges, some open-frame buildings, transmission poles and sculptures.
What is the difference between Corten A and Corten B?
CorTen A is often used for aesthetic purposes It is not recommended for use where the structure is subject to vibration. CorTen B is more suitable for load-bearing structures than it is more resistant to vibration or earthquake, and is often chosen due to its aesthetics and more uniform stains.
What is Corten B?
Corten B is a weather resistant steel which is better suited for heavy and load bearing structures. The material forms its own protective layer when exposed to atmospheric elements. Essentially, the top layer corrodes which then protects the steel beneath it.
