Structural steel is a standard construction material, made from specific grades of steel and formed in a range of industry standard cross-sectional shapes (or ‘Sections’). Structural steel grades are designed with specific chemical compositions and mechanical properties formulated for particular applications.

In Europe, Structural Steel must comply with the European Standard EN 10025 a Governed by the ECISS (European Committee for Iron and Steel Standardization) a subset of CEN (European Committee for Standardization.

There are many examples of European grades of structural steel such as; S195, S235, S275, S355, S420, S460 etc. However, for the purposes of this article we will focus on the Chemical Composition, Mechanical Properties and Applications of S235, S275, S355. Three common structural steel grades used in all manner of Construction projects across the EU.

Inline with the European Standard classifications, Structural steel must be referenced using standard symbols including but not limited to: “S”235″J2’‘K2’’C’’Z’’W’’JR’’JO’’

Where:

• S – denotes the fact that it is Structural
  Steel
• 235 – related to the minimum yield strength
  of the steel (tested at a thickness of 16mm)
• J2 /K2/ JR / JO – material toughness in relation to the
  Charpy impact or ‘V’notch test methodology
• W – Weathering Steel (Atmospheric
  Corrosion Resistant)
• Z – Structural steel with improved
  strength perpendicular to the surface
• C – Cold-formed

Depending on the manufacturing process, chemical composition and relevant application, further letters and classifications might be used to reference particular grades/products of structural steel.

The EU Standard classifications are inherently not a global standard and therefore a number of corresponding grades with the same Chemical and Mechanical properties may be used in other parts of the world. For example, Structural Steel fabricated for the US market must be specified in accordance with the ASTM (American Society for Testing and Materials)International guidelines and will be referenced with an ‘A’ and then the relevant Grade such as A36, A53 etc.