Structural Steel: S235, S275, S355 (3) - Mechanical Properties

Mechanical Properties of Structural Steel – S235, S275, S355

The Mechanical Properties of Structural Steel are fundamental to its classification and hence, application. Even though Chemical Composition is a dominant Factor of the Mechanical Properties of steel, it is also very important to understand the minimum standards for the Mechanical Properties (Performance characteristics) such as; Yield Strength and Tensile Strength.

Yield Strength

The yield strength of structural steel measures the minimum force required to create a permanent deformation in the steel. The naming convention used in European Standard EN10025 refers to the Minimum Yield strength of the steel grade tested at 16mm thick.

Structural Steel Grade at 16mm	Minimum Yield Strength at nominal thickness 16mm
	ksi	N/mm2 (MPa)
S235	33 000 ksi	235 N/mm2
S275	36 000 ksi	275 N/mm2
S355	50 000 ksi	355 N/mm2

Tensile Strength

The Tensile Strength of Structural steel relates to the point at which permanent deformation occurs when the material is pulled or stretched laterally along its length.

Structural Steel Grade	Tensile Strength MPa at Nom thickness between 3mm and 16mm
S235	360 – 510 MPa
S275	370 – 530 MPa
S355	470 – 630 MPa

Typical Structural Steel ‘Sections’ / Cross-Sectional Shapes

Structural Steel comes in many Grades but is normally sold pre-formed with a defined cross-sectional shape, designed for specific applications. For example, it is common to find Structural Steel sold in: I-Beams, Z-beams, Box Lintels, HSS (Hollow Structural Section), L shaped, Steel Plate etc.

Depending on the desired application, an engineer will specify a grade of steel (Often to meet minimum strength, max weight and or weathering requirements) and the sectional shape, relative to the desired location and expected load to be carried or job to be performed.

Structural Steel: S235, S275, S355 (3) - Mechanical Properties