S355J0W is a high-strength, low-alloy weathering structural steel plate, with its designation conforming to the European standard EN 10025-5:2019 "Hot rolled products of structural steels—Part 5: Technical delivery conditions for structural steels with improved atmospheric corrosion resistance". This standard is widely adopted across Europe and many other countries as the technical specification for weathering steels, and S355J0W is one of its key grades.
The designation "S355J0W" has a clear meaning:
"S" stands for "Structural steel," indicating its use in load-bearing structures.
"355" indicates the specified minimum yield strength of 355 MPa, placing it in the medium-to-high strength category with good load-bearing capacity.
"J0" represents the quality grade, where "J" is the code for the impact test series, and "0" specifies that the material must undergo a Charpy V-notch impact test at 0°C, with an average absorbed energy (KV2) of no less than 27 J. This ensures sufficient toughness to resist brittle fracture under ambient and low-temperature conditions.
"W" stands for "Weathering," clearly identifying its resistance to atmospheric corrosion.
The primary application of S355J0W steel plate is in the fabrication of various buildings and engineering structures that are permanently exposed to the atmosphere. Thanks to its excellent overall performance, it has become a key material in modern infrastructure construction. Typical applications include:
Bridge Engineering: Widely used in main girders, bridge decks, and trusses for highway and railway bridges—critical load-bearing components—significantly reducing bridge maintenance costs and lifecycle expenses.
Architecture: Used in exposed structural steel for high-rise buildings, large-span space structures, sports arenas, airport terminals, as well as building façade cladding and art sculptures, where its naturally formed reddish-brown rust patina combines structural functionality with unique aesthetic value.
Transportation: Used in the manufacture of containers, truck bodies, traffic signal towers, and noise barriers.
Industrial Facilities: Used in transmission towers, substation frameworks, storage silos, pipe supports, and wind turbine towers for outdoor installations.
Its main characteristics include:
Excellent Atmospheric Corrosion Resistance: By adding alloying elements such as copper (Cu), chromium (Cr), and nickel (Ni), the steel forms a dense, stable, and well-adhered protective rust layer in the atmosphere. This layer effectively prevents oxygen, moisture, and pollutants from further corroding the underlying base metal, giving it corrosion resistance far superior to ordinary carbon steel, typically 4 to 8 times greater.
High Strength and Good Toughness: The high yield strength of 355 MPa meets the load-bearing requirements of structural engineering, while the J0-level impact toughness ensures safety and reliability in low-temperature environments.
Maintenance-Free: In most atmospheric environments, S355J0W can be used without painting, eliminating the need for regular repainting, significantly reducing long-term maintenance costs and environmental impact.
Good Weldability and Workability: Easy to cut, bend, and weld, facilitating construction and fabrication.
Ultrasonic Testing (UT)
A key non-destructive testing technique that uses high-frequency sound waves to detect internal flaws in steel plates. The probe emits sound waves, which reflect when encountering defects such as cracks or inclusions. The receiver captures the echoes, enabling precise determination of defect location and size. With high sensitivity, strong penetration, and fast inspection speed, UT effectively ensures internal quality, widely used in the production of heavy plates, pressure vessel plates, and other high-end products to guarantee safety and reliability.
Magnetic Particle Testing (MT)
A common surface inspection method that magnetizes the workpiece, causing leakage magnetic fields at surface or near-surface defects like cracks or inclusions, which attract magnetic particles to form visible indications. Simple to operate and highly sensitive, MT is suitable for rapid inspection of surface and near-surface flaws in ferromagnetic materials, widely used for online or offline inspection of plate edges, ends, and welds, ensuring product quality and safety.
Penetrant Testing (PT)
A non-destructive method for detecting surface-breaking flaws. A penetrant liquid is applied to the cleaned steel surface, allowing it to seep into defects such as cracks or pores. After removing excess penetrant, a developer is applied, causing the trapped penetrant to bleed out and form visible indications. Simple and cost-effective, PT is suitable for inspecting surface defects in various non-porous materials, commonly used for welds, castings, and complex components, effectively ensuring surface quality of steel plates.
