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What is S275 grade steel?

What is S275 steel?

S275 steel is a general-purpose structural steel that is used widely in the construction industry  due to its strength and workability properties.  S275 is a low carbon steel most commonly supplied as plate, round, or flat bar.

Steel classification is regulated within Europe by the European Committee for Iron and Steel Standardisation, S275 steel complies with EN 10025 standard in Europe but may be referred to as A570Gr40 in the United States. Within Europe, all metals must meet specific criteria for their classification which includes rigorous regulation regarding strength and chemical composition.

For classification purposes within Europe, ‘S’ refers to the fact that this is structural steel. ‘275’ is a reference to the yield strength. Yield strength must meet the minimum requirement of 275 N/mm2. Testing for strength is carried out on sample material that is up to 16 mm thick.

How strong is S275 steel?

The strength of metal is tested using four strength scales – tensile strength, yield strength, impact strength and compressive strength. The most commonly used scales for testing the strength of steel are tensile and yield, these give metal its classification as these scales define mechanical properties. The tensile strength of S275 steel in MPa, tested on nominal thickness s275 of a range between 3 mm and 16 mm, is 370 – 530 MPa. The yield strength, tested on material 16 mm thick, is 36,000 psi/ 275 N/mm2.

 

Physical and mechanical properties of S275 steel.

 

PHYSICAL PROPERTY

VALUE

DENSITY

7800 KG/M³

Melting Point

1460 °C

Modus of Elasticity

210 GPa

Electrical Resistance

0.20-0.25 µΩm

Thermal Conductivity

50 W/m °k

Thermal Expansion

11 µm/m-k

 

 

MECHANICAL PROPERTY

VALUE

Yield Strength

275 N/mm²

Tensile Strength

370 - 530 N/mm²

Shear Modulus

80 GPa

Hardness Vickers

115 - 154 Vickers - HV

Elongation (in 200 mm)

20%

 

Manufacture.

The process of manufacturing S275 steel is not dissimilar to the manufacturing of other grades of steel. Iron ore is added to a furnace alongside coal and this produces molten steel once the impurities have burned off. Alloying elements such as sulphur and manganese are then added to the molten steel and adjusted to get the correct chemical composition, as designated by the classification. Ingots are produced once the steel has been poured and allowed to cool. The final process is to hot roll the ingots to give them their final form.

 

Chemical composition of S275 steel (% weight).

CARBON

SILICON

MAGNESIUM

POTASSIUM

SULPHUR

IRON

0.25 max

0.05 max

1.6

0.04

0.05

Balance

 

Popular uses for S275 steel.

Steel is used the world over in substructures and superstructures within construction, S275 is used in construction to produce rolled steel joists because of its strength and mechanical properties. As a low carbon steel, S275 is easily machinable and has good welding properties which makes it a popular choice across oil, gas, automotive, and aeronautical industries to construct frames, joist supports, brackets, vehicle and chassis parts, and general maintenance applications.

Corrosion resistance and heat treating.

As S275 does not contain large amounts of chromium or nickel it is  susceptible to corrosion so requires additional applications for corrosion-resistance such as metal paint or red oxide primer and paint.

The low carbon content of S275 steel makes it unsuitable, as with all low carbon mild steels, for induction and through hardening treatments. S275 is suited to case-hardening or gas/ pack carburising.

To find out much more about different steel grades, read our in-depth technical guide available here.