If you’re involved in steel structure design or procurement, you’ve no doubt encountered this situation: the drawings specify the European standard S355J2W, but you only have other weathering steels in stock, or the client requests a substitute using American standard materials. So the question arises—what material can S355J2W actually be replaced with? And will the performance be compromised as a result?

Today, we’re going to get to the bottom of this.

1. What is S355J2W?

S355J2W is a weathering structural steel grade defined in the European standard EN 10025-5. Put simply, it is a type of steel that ‘rusts but is not affected by rust’. Its naming convention is as shown in the table below:

The most distinctive feature of this steel is that it ‘uses rust to prevent rust’. Through the addition of alloying elements such as copper, chromium and nickel, it forms a dense, stable oxide layer—commonly known as a ‘rust skin’—on its surface when exposed to the atmosphere. This rust skin prevents oxygen and moisture from further corroding the underlying metal, resulting in corrosion resistance that is two to eight times greater than that of ordinary carbon steel. For this very reason, S355J2W is widely used in outdoor structures with high weather resistance requirements, such as bridges, exposed building structures, railway rolling stock, port machinery, transmission pylons and shipping containers.

2. Equivalent materials under other standards

2.1 American standard: ASTM A588 Grade B

This is the most direct and commonly used equivalent option. S355J2W and ASTM A588 Grade B are highly consistent in terms of chemical composition and mechanical properties; both have a yield strength of 355 MPa, and their tensile strengths fall within the range of 470 to 630 MPa. A588 Grade B is itself the primary grade of American weathering structural steel, widely used in bridges and building structures. In practical engineering applications, provided the project accepts materials conforming to American standards, substituting A588 Grade B for S355J2W presents virtually no issues.

2.2 Chinese Standards: GB/T Q355NH or Q355GNH

In the context of Chinese weathering steel, the grades most closely corresponding to S355J2W are Q355NH and Q355GNH, which comply with the GB/T 4171 standard. Both grades have a yield strength of 355 MPa and achieve their weathering properties through the addition of alloying elements such as copper, chromium and nickel. Therefore, if a project requires the use of Chinese standard materials to replace S355J2W, the Q355NH series is the preferred choice.

2.3 Japanese Standard: JIS G3125 SPA-H

In Japan, SPA-H is the equivalent grade to Corten B, and Corten B and S355J2W are essentially the same material. Furthermore, SMA50CP in the JIS standard is also equivalent to S355J2W. For Japanese projects or situations where materials need to be sourced from Japan, SPA-H is a highly reliable alternative.

2.4 Global Standard: Corten B

Regardless of the standards used, there is a common understanding within the industry that S355J2W is Corten B. Corten (full name COR-TEN, meaning ‘weathering steel’) is a registered trademark of U.S. Steel, but has now essentially become a generic term for all weathering steels. Corten B is the grade suitable for heavy-duty structures, whilst S355J2W is the equivalent of Corten B within the European standards system.

2.5 For greater clarity, I have compiled the main equivalence relationships into a table:

3. Before making a substitution, there are a few details you need to bear in mind

Although the grades listed above can be used as equivalent substitutes, there are a few details that must not be overlooked when actually making the substitution.

3.1 Temperature grade for impact toughness.

The ‘J2’ in S355J2W specifies that impact testing must be conducted at -20°C; this is the primary distinction between it and S355J0W (zero-degree impact). If your project has specific requirements for low-temperature impact performance, the substitute material must also meet the same temperature grade.

3.2 Applicable thickness range.

The actual delivery condition and mechanical properties of the same equivalent grade across different standards vary with thickness. The tensile strength of S355J2W decreases as thickness increases; when the thickness exceeds 100 mm, the tensile strength drops from 470–630 MPa to 450–600 MPa. Therefore, when selecting a substitute material, it is essential to verify the performance parameters of the substitute grade at the corresponding thickness.

3.3 Welding Process and Welding Material Compatibility.

S355J2W possesses good weldability. Research has been conducted using a new Ni-Cu1-1 welding wire to weld S355J2W weathering steel for high-speed trains, with results indicating excellent microstructure and mechanical properties in the welded joints. If other weathering steels are used as substitutes, the welding materials must also be adjusted accordingly; they cannot simply be carried over.

4. Material Selection Recommendations

Having said all that, how should one actually go about making a choice? Our recommendations are as follows:

4.1 Projects for Export to the EU / Europe

Simply procure S355J2W directly; there is no need to go to the trouble of seeking alternatives, as it is fully compliant with all certifications, standards and certificates.

4.2 Projects for Export to North America / North American Regions

Using ASTM A588 Grade B is the safest option, with no issues regarding performance or cost.

4.3 Projects Exporting to China / Domestic Chinese Projects

Using Q355NH or Q355GNH as substitutes is entirely feasible. The chemical composition, strength, weather resistance and impact resistance are fully compatible, and multiple domestic steel mills can supply these consistently. The procurement channels are well-established, and the prices are more competitive.

4.4 Cross-border Procurement / Projects Involving Multiple National Standards: Corten B is a universal solution – ‘Corten B’ is a term understood by virtually all global suppliers.

A final reminder: Regardless of the alternative chosen, the design codes of the project location and client requirements must take precedence. Material equivalence is merely a technical approximation; final confirmation should ideally be verified through comparison of Material Test Certificates (MTCs) and necessary performance retesting.

5. Points to Note

5.1 Performance Verification

Requirements regarding chemical composition, mechanical properties and corrosion resistance indices may vary slightly between different standards. When substituting materials, it is essential to carefully verify the project requirements against the actual performance parameters of the replacement material.

5.2 Design Specifications

The project’s original design specifications may stipulate materials conforming to a specific standard. Before proceeding with a material substitution, it is advisable to confirm with the design team or client to ensure the alternative complies with relevant design specifications and acceptance criteria.

5.3 Comprehensive Assessment

In addition to the yield strength requirements for S355J2W, the ‘J2’ designation also indicates requirements for low-temperature impact toughness at -20°C. When selecting an equivalent material, it is necessary to ensure that all key performance indicators are met.