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Structural Steel – S235, S275, S355 Chemical Composition, Mechanical Properties and Common Applications

Structural Steel – S235, S275, S355 Chemical Composition, Mechanical Properties and Common Applications

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.

US Equivalent Grades

EU

US

S235

A283C

S275

A570Gr40

S355

A572Gr50

In most countries Structural Steel is regulated and must meet a minimum
specific criterion for Shape, Size, Chemical Composition, strength etc.

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

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 ¨C 510 MPa

S275

370 ¨C 530 MPa

S355

470 ¨C 630 MPa

Applications of Structural Steel

Structural steels are used in many ways and their application can be
diverse. They are particularly useful because they offer the unique
combination of good welding properties with guaranteed strengths.
Structural Steel is an extremely adaptable product and is often favoured
by the engineer trying to maximise strength or s structure while
minimising its weight.

It will come as no surprise that the construction industry is the
biggest consumer of Structural Steel, where it is used for all manner of
purposes and employed at diverse scales. Whether a small box lintel is
used to carry the load of a structural wall in a residential property or
a vast I-beam is bolted in place to hold the road surface on a bridge,
structural steel can be specified, designed and fabricated for the job.

  • High Rise Buildings / Skyscrapers
  • Houses
  • Factories
  • Offices
  • Shopping Malls
  • Train Tracks
  • Road barriers
  • Bridges

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