S355 Structural Steel

S355 is a widely used high-strength structural steel. The “355” designation refers to a minimum yield strength of approximately 355 MPa for specified thickness ranges. Compared with conventional structural steels such as A36, S355 offers higher strength and load-bearing capability while maintaining good weldability and machinability.

Appearance & Properties

Color: Dark gray to gray-black

Density: Approx. 7.85 g/cm³

Yield Strength: Up to approximately 355 MPa minimum, depending on thickness and grade

Tensile Strength: Approx. 470–630 MPa, depending on grade and thickness

Corrosion Resistance: Poor

Machinability: Good

Weldability: Good

Magnetism: Magnetic

Surface Finishes: Hot-dip galvanizing, zinc coating, blasting, painting, powder coating, etc.

Typical Applications

S355 Structural Steel is widely used in construction machinery, industrial equipment, energy systems, transportation, structural fabrication, and large automation equipment.

Typical parts include machine frames, bases, load-bearing brackets, connection plates, mounting plates, heavy-equipment structures, welded frames, and large CNC machined structural components.

Advantages

• Higher strength and load capacity than conventional low-carbon structural steels

• Good weldability and machinability

• Suitable for large load-bearing and welded structures

• Widely available in various plate sizes

• Good balance of strength, manufacturability, and cost

Limitations

• Poor corrosion resistance and usually requires surface protection

• Relatively heavy compared with lightweight alloys

• Not ideal for high-wear or extremely high-hardness components

• Impact toughness and mechanical requirements vary among different S355 subgrades