S355J4W Weathering Structural Steel Plate is a high-performance low-alloy steel designed for outdoor applications requiring exceptional resistance to atmospheric corrosion. Compliant with EN 10025-5, this grade features a minimum yield strength of 355 MPa (for thickness ≤16mm), ensuring robust structural integrity. The "J4" denotes its ability to withstand impact tests at -30°C with a minimum absorption energy of 27J, making it suitable for cold-climate environments.
Key alloying elements like copper (0.25-0.55%), chromium (0.40-0.65%), and nickel (≤0.65%) promote the formation of a dense, adherent oxide layer on the surface, significantly retarding corrosion compared to ordinary carbon steel. This "weathering" property reduces the need for frequent painting or coating, lowering long-term maintenance costs by up to 50%.
Mechanically, S355J4W offers a tensile strength of 470-630 MPa and an elongation at break of ≥21%, balancing strength and ductility. Its weldability is favorable when proper techniques are applied, though control of heat input is recommended to preserve corrosion resistance.
Typical applications include bridges, railway vehicles, offshore structures, and industrial steel frameworks exposed to harsh weather. Compared to S355J2W (which meets -20°C impact tests), S355J4W provides enhanced cold-weather performance. In China, it is comparable to Q355NH/Q355GNH, though minor differences in chemical composition may exist.
For engineers and fabricators, S355J4W delivers a cost-effective solution for durable, low-maintenance structures in corrosive environments, combining structural reliability with environmental adaptability.
FAQ
Q1: What standard does S355J4W follow?
A: It complies with EN 10025-5 for weathering structural steels.
Q2: What gives S355J4W its corrosion resistance?
A: Alloying elements like copper, chromium, and nickel form a protective oxide layer.
Q3: At what temperature is the impact test conducted for S355J4W?
A: The impact test is performed at -30°C with ≥27J energy absorption.
Q4: Where is S355J4W commonly used?
A: It's used in bridges, towers, containers, and outdoor steel structures.
Q5: How does S355J4W differ from S355J2W?
A: S355J4W has a lower impact test temperature (-30°C vs. -20°C for J2W).
