Structural Steel - S235, S275, S355 Chemical Composition, Mechanical Properties and Common Application

　Introduction

　　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 steels must be referenced using standard symbols including but not limited to: "S"235"J2’‘K2’’C’’Z’’W’’JR’’JO’’

         US Equivalent Grades

EU	US
S235	A283C
S275	A570Gr40
S355	A572Gr50

Chemical Composition of Structural Steels - S235, S275 and S355

The Chemical composition of Structural Steel is extremely important and highly regulated. It is a fundamental factor which defines the Mechanical properties of the steel material. In the following table you can see the Max % levels of certain regulated elements present in European Structural steel grades S235, S275 and S355.

Grade	C%	Mn%	P%	S%	Si%
S235	0.22 max	1.60 max	0.05 max	0.05 max	0.05 max
S275	0.25 max	1.60 max	0.04 max	0.05 max	0.05 max
S355	0.23 max	1.60 max	0.05 max	0.05 max	0.05 max

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