Weathering steel falls under the category of low carbon steels. It contains alloying elements like copper, chromium, silicon, and phosphorus, which are mixed with carbon and iron atoms.
Let’s dive into what weathering steel is and how it can be used in welding.
What is Weathering Steel?
Weathering steel is a special type of steel known for its high strength and resistance to corrosion caused by environmental factors such as air and moisture. Its unique chemical makeup allows it to develop a protective outer layer of rust (also called ‘patina’). This layer acts as a shield, preventing further corrosion from reaching the deeper parts of the steel.
Also known as Corten steel, this material was originally developed by U.S. Steel in 1933 and was trademarked as Cor-Ten. The name comes from two key features: corrosion resistance and tensile strength. Over time, the American Society for Testing and Materials (ASTM) established it as a standard product.
Welding Weathering Steel
The process of welding and weathering steel is quite straightforward. It welds in a similar manner to common low-carbon steels like ASTM A36 and ASTM A572.
The American Welding Society (AWS) provides two main welding codes—D1.1 for structural welding and D1.5 for bridge welding—which cover the proper methods for welding weathering steels across different conditions.
Since weathering steel comes in various levels of strength, the type of filler metal used for welding can differ depending on the application. It’s essential to match the mechanical properties of the filler metal—such as tensile strength, yield strength, and toughness—with the design requirements of the project. In most cases, the filler metal should meet or exceed the minimum strength properties of the base steel to ensure the structure remains strong and reliable.
Corten Steel Texture
Corten steel has a distinctive rusty appearance with an orange-brown color. Its seamless texture adds a stylish and attractive finish to any application. Welders can work with it easily, without needing to mix chemicals to achieve the rusty look.
Corten Steel Properties
Corten steel is valued for several key properties:
- Resistant to corrosion
- Strong and durable
- Flexible and ductile
- High structural integrity
- Lightweight
- Visually appealing
- Requires minimal maintenance
Corten Steel Specifications
The main trademark for this product is COR-TEN, but there are also standard specifications set by ASTM, which include:
- A588: Structural weathering steel for panels, shapes, plates, and bars
- A242: Steel plates up to 1.5 inches thick
- A606-4: Sheets and coils
- A847: Tubes and pipes
- A871-65: Steel plates with a minimum yield strength of 65 ksi
- A709-50W: Steel plates for bridge construction
Weathering steel is available in two grades: Corten A (A242) and Corten B (A588).
Uses and Applications of Corten Steel
Corten steel is popular for its practical use and its aesthetic qualities. Some of its common applications include:
- Engineering projects
- Architectural designs
- Construction of buildings and bridges
- Outdoor sculptures
- Marine transport
- Roofing and walls
- Bike racks
- Garden planters
- Tree grilles
Corten Steel Prices
Corten steel tends to be more expensive compared to other steel grades. The price varies depending on the grade, properties, and specifications of the steel, as well as the manufacturer.