Mechanical Properties of S355K2G1W Weathering Steel Plates

Yield strength (ReH). Minimum 355 MPa for thicknesses up to 16mm. That's the heart of the "S355" designation. As plates get thicker, yield strength gradually decreases—but even at 100mm thickness, you'll still see at least 275 MPa. For comparison, ordinary structural steel S235 offers only 235 MPa at the low end.

Tensile strength (Rm). Falls between 470 and 630 MPa, depending on thickness. This spread gives fabricators flexibility. Lower end of the range suits cold-formed sections. Higher end delivers extra muscle for heavily loaded joints.

Elongation (A). Minimum 20–22% on standard test specimens. That's respectable for a high-strength steel. It means the material won't snap without warning when bent or stretched during forming. You can roll it, brake it, and curve it without constant fear of cracks.

Impact toughness (the "K2" part). This is where S355K2G1W truly shines. Guaranteed 27J minimum in Charpy V-notch testing at -20°C. For thinner plates, often tested at full size. For thicker sections, using subsize specimens with proportionally lower requirements. What this means in plain language: hit this steel with a sharp blow on a freezing winter day, and it won't shatter.

A note on G1W vs G2W mechanics. Mechanically, they're nearly identical. Both meet the same S355 yield requirement and K2 impact rating. The difference lies mainly in chemistry and corrosion optimization—not in how they carry loads.

Practical takeaway. For bridges, crane components, railcars, and building frames that face real winters, S355K2G1W delivers dependable numbers. Just match thickness to the required loads and specify the correct impact testing frequency for your application.