Editorial Feature

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

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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, which is governed by the European Committee for Iron and Steel Standardization (ECISS), a subset of the European Committee for Standardization (CEN).

There are many examples of European grades of structural steel – for example, S195, S235, S275, S355, S420, and S460. For the purposes of this article, we will focus on the chemical composition, mechanical properties, and applications of S235, S275, and S355, which are three common structural steel grades used in all manner of construction projects across the EU.

In line 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, and JO, where:

  • ‘S’ denotes the fact that it is structural steel;
  • ‘235’ which relates to the minimum yield strength of the steel (tested at a thickness of 16mm);
  • ‘J2’, ‘K2’, ‘JR’, and ‘JO’ all demonstrate the material toughness in relation to the Charpy impact or ‘V’ notch test methodology;
  • ‘W’ is weathering steel (atmospheric corrosion-resistant);
  • ‘Z’ represents structural steel with improved strength perpendicular to the surface, and
  • ‘C’ is cold-formed.

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

The EU standard classifications are 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 steels fabricated for the US market must be specified in accordance with the American Society for Testing and Materials (ASTM). International guidelines are referenced with an ‘A’ and then the relevant grade, for example, A36 or A53.

EU and 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 and strength.

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. In the following table, you can see the maximum percentage levels of certain regulated elements present in European structural steel grades S235, S275, and S355.

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.

EU 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

The chemical composition of structural steel is incredibly important to the engineer and will change with specific grades depending on their intended use. For example, S355K2W is a structural steel that has been hardened, denoted by K2, and has been designed with a chemical composition to withstand increased weathering - W. Therefore, this grade of structural steel will have a slightly different chemical composition to the standard S355 grade.

Mechanical Properties of Structural Steel - S235, S275, S355

The mechanical properties of structural steel are fundamental to its classification and application. Even though chemical composition is a dominant factor in determining the mechanical properties of steel, it is also very important to understand the minimum standards for the mechanical properties or performance characteristics, such as yield strength and tensile strength, which are described in more detail below.

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

psi

N/mm2 (MPa)

S235

33 000

235 N/mm2

S275

36 000

275 N/mm2

S355

50 000

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, hollow structural section (HSS), L-shaped and steel plate.

Depending on the desired application, an engineer will specify a grade of steel -usually to meet minimum strength, maximum weight and possibly weathering requirements, as well as the sectional shape - relative to the desired location and expected load to be carried or job to be performed.

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 favored by engineers trying to maximize strength or ‘S’ structure while minimizing its weight.

It will come as no surprise that the construction industry is the biggest consumer of structural steel, where it is used for a number of purposes. 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 any type of job.

This article was updated on 7th August, 2019.

 

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Comments

  1. Kashif Khawaja Kashif Khawaja United States says:

    How can I calculate the yield strength suitable for my load?

    e.g for HEA 340 what yield strength is sufficient to carry 5 ton moving crane?

    • Paul Murphy Paul Murphy United Kingdom says:

      Hi Kashif,

      I unfortunately cannot give you a definitive answer. You would have to contact somebody that has access to a load cell programme i.e. an architect or someone who offer finite element analysis.

      The highest grade available from stock is 355N/mm yield at this size though.

      If you require any further information please contact [email protected]

  2. sujil suji sujil suji Malaysia says:

    Dear Sir,
                  How can I get the P no of this S275  Steel

    • Paul Murphy Paul Murphy United Kingdom says:

      Dear Sujil,

      Are you referring to Phosphorus level of S275 or are you referring to the Pressure application equivalent (P275)?

  3. Rahul Pratap Rahul Pratap India says:

    PWHT REQUIRED ON S355 GRADE MATERIAL

    • Ramesh Kannan Ramesh Kannan Singapore says:

      Please can you any one advise my WPS is Qualified AWS D1.1 5-unlimited with charpy and without charpy...group II Material Gr X52...can use 355 Material this WPS?

      • Biju Abraham Biju Abraham India says:

        Is steel gare S275 is equivelant to ASTM A 36

  4. Andrew Collinson Andrew Collinson United Kingdom says:

    Hi,
    Is there any simple field test for determining if steelwork is S275 or S355?
    Thanks
    Andrew

    • Paul Murphy Paul Murphy United Kingdom says:

      Hi Andrew,

      The only field test I believe you can be referring to is a PMI test.

      It's a non-destructive spectrographic chemical analysis.

      It won't determine which grade it is but might prove it can't be S355.

      Hope that makes sense.

      Kind Regards,
      Paul Murphy (Masteel UK Ltd)

  5. Suresh Surendran Suresh Surendran U.A.E. says:

    can 275 and 355 grade welded using the same wps

  6. Suraj Ranaweera Suraj Ranaweera Sri Lanka says:

    can you tell me what can we use as alternative steel for S355.. Japanees Chinese & American please

    • Edir Thamrin Edir Thamrin Malaysia says:

      EH36 or ASTM A572 Gr50

  7. sumeet malik sumeet malik India says:

    What is the difference between S355H and S355N/H. Is there any difference in yield strength values?

  8. emeline marteja emeline marteja Jordan says:

    My client required  ASTM A283GR C Group 1,, we offered S275 JR for Steel Flat Bar. Is it ok for them to use S275 JR as an alternative.  We don't have A283 GR C in stock right now.  Please assist.

  9. Arun Kuttikkattu Vijayan Arun Kuttikkattu Vijayan U.A.E. says:

    What is the equivalent grade of S275 in american standard?

    • Paul Murphy Paul Murphy United Kingdom says:

      Arun,

      Closest American equivalent would be either ASTM A36 or A283 GR C

  10. Ashraf Asagifi Ashraf Asagifi Libya says:

    I'd like to say : thanks , could you possibly   sending me the source of this article or any official related to ?? , the best article , I've ever read .
    thank you again .

  11. Shridhar Rai Shridhar Rai India says:

    Is E250 BR is equivalent to S275?

  12. Amira El Ayeb Amira El Ayeb Tunisia says:

    Hey , How can i find this material in Solidworks ?

    • Ashraf Asagifi Ashraf Asagifi Libya says:

      Amira are you steel strcture engineer

    • AHMARFARMAN AHMARFARMAN India says:

      you can only find different pure forms of alloys like mild steel , with density 7850 and yst 210 ,but you cant get through different grades of steel .

  13. Imran Zada Imran Zada Islamic Republic of Pakistan says:

    the values of yield strength is not in ksi,like given . Please make correction it should be   33 000 psi for S235 instead of  33000 ksi.

  14. Didik Setiono Didik Setiono Indonesia says:

    Dear Sir,
    Did S235 J2 equivalent with A333 Gr6 or A36 ???
    And S355 J2 equivalent with A572 Gr.50 ???

    Thanks for your attention
    Didik S

    • Paul Murphy Paul Murphy United Kingdom says:

      Hello Didik,

      Generally speaking S235 will not be certified as S235J2 you would tend to see this grade certified in S235JR with a EN10204 2.2 certificate. This grade is not interchangeable with A333 GR 6 (pipe specification) or ASTM A36 (Sheet/plate & structural sections specification).

      The EN equivalent of ASTM A36 would be S275JR.

      S355J2+N/M is the direct EN equivalent of ASTM A572 GR 50.

      Hope this helps.

  15. Tracy Kearney Tracy Kearney Ireland says:

    I am designing using S275 grade steel but I understand that there is no cost difference between the S275 and S355. Is this correct? Is S275 an obsolete grade?

    • Paul Murphy Paul Murphy United Kingdom says:

      Hi Tracy,

      I'm afraid the information you have is incorrect. S275 is not an obsolete grade and is still a mainstay in the construction industry perhaps even more so than S355 material.

      S355 is a higher grade of material compared to S275 and therefore there is a cost difference between the two grades.

      Hope this helps.

      Paul Murphy

      • Apex Cary Apex Cary India says:

        Yes
        we are using both S235JR and S355J2+N

        can you pl confirm what is 'N'?

        Thanks

        • A M A M India says:

          Normalized steel process

  16. P K Unnikrishnan P K Unnikrishnan India says:

    In the chemical composition of steel what is W stands for

  17. Subho Chatterjee Subho Chatterjee India says:

    IS  S235jR SUITABLE FOR MARINE USE ? THIS IS PROPOSED TO BE USED AS PIPE FLANGE FOR LOW PRESSURE SYSTEM ( UPTO 7 BAR WORKING PRESSURE ) . STRENGTHWISE , IT IS OK .
    SUBHO CHATTERJEE

  18. Pushparaj P.V. Pushparaj P.V. U.A.E. says:

    Can I use the ASTM E570 instead of S275JR for handrails. Which one is the higher grade.

  19. Stephen Taylor Stephen Taylor United Kingdom says:

    is S355NLW Grade Structural Steel readily available in UK

  20. Muhammad Farhan Muhammad Farhan Portugal says:

    What is the approximate cost of steel grade S355 and S690?

  21. E. Nussbacher E. Nussbacher Belgium says:

    One of our contractors claims that S235 is the standard material used for most industrial steel profiles ans if one wants S355 - it will require a special order with long lead times.
    Is this correct?

    • AHMARFARMAN AHMARFARMAN India says:

      yes ,

  22. Chellam Muniyandi Chellam Muniyandi Kuwait says:

    Anybody help me provide the chemical & Physical properties of BS:4592-5 Steel plate for floor purpose...

  23. Chellam Muniyandi Chellam Muniyandi Kuwait says:

    I need chemical & physical properties of BS:4592-5 ....Anybody possible to help?

  24. Hamdi Ismail Hamdi Ismail Malaysia says:

    Hi,

    - S355 grade need to preheat before welding process? if Yes, what is the preheat temperature and how long to preheat?  how many % the strength reduce (S355 grade) for built up plate / after preheat?

  25. Keshav Bhojwani Keshav Bhojwani Curaçao says:

    Hi, I am trying to order a steel structure that is approx 11m high and has 2 stories (ground floor and 2nd floor) . i am getting an offer from Europer (more reliable) for S235JR steel and one from china for s355JR (Q345B) steel. The second floor is warehousing and needs to hold a lot of weight. A pallet that we have (for example) weighs over 800kgs. the chinese factore claims that S235JR is NOT sufficiently strong to hold this kind of weight and the steel construction HAS to be S355JR, while the European company claims different. the structure is 27m wide by 36m long and the columns are 9m and 6m apart respectivly on the ground floor and the second floor is freespan all the way. does anyone have any advise what steel would be best suited for this project?

    thank you!

    • A M A M India says:

      s355JR

    • AHMARFARMAN AHMARFARMAN India says:

      as 355 denote yst

  26. Jeri Cadi Jeri Cadi Philippines says:

    can S355 be welded in A36 steel?

  27. Jeri Cadi Jeri Cadi Philippines says:

    can S355 be welded to A36 steel? What is the recommended welding process/method?

  28. Ritchie Hutton Ritchie Hutton United Kingdom says:

    We had material supplied via a Russian mill as grade S235. When we tested it with an independant UKAS testing facility the yield and tensile closely matchedthat of S355. Can we request that the material be upgraded to S355 and request a re-issue of the mill certs?

  29. Abdallah Aschkar Abdallah Aschkar Ghana says:

    Hello
    I am constructing a vertical tank from S235JR steel, and I would like to know wether I can use S275JR steel for an accessory, namely the  windgirder at the top
    The question is are the two types of steel weldable together? The electrode I am using on site is of grade ER 7018

  30. Hafsa Byah Hafsa Byah Morocco says:

    I NEED INORMATION USE  OF S355 IN MARINE STRUCTURES
    does anyone have any advise what steel would be besT

  31. Pradip Manekar Pradip Manekar Bahrain says:

    I need to ask the S275 grade ---if not available, then can we use C22 grade materials.

  32. Robert Emrys Long Robert Emrys Long Denmark says:

    corrosion, is there a difference between the corrosion in salt water of S 235 and S355
    where can i find documentation
    thankyou

  33. ASAD AHMADI ASAD AHMADI Iran says:

    what is the meaning of b at the end of S235 JRB

  34. Muhammad Muslim Muhammad Muslim Islamic Republic of Pakistan says:

    dear all can anyone send me (S235) materail PQR and wps at
    [email protected]
    thanks

  35. MUDD SID MUDD SID Islamic Republic of Pakistan says:

    I need to ask the S235 grade ---if not available, then can we use A36 grade materials.

  36. MARTIN HOSSAIN MARTIN HOSSAIN Trinidad and Tobago says:

    what type of steel mat'l is -- S355 compatable to, mild steel, en19, want to make sleeve spacers for tightening bolts, and does this S355 comes in round stock shaft mat'l

  37. Senad Kudumović Senad Kudumović Sweden says:

    Hi,

    I would like to know more about content of Co (cobalt) and Ni (nickel) in S355, since that is not stated in chemical properties table? Can you please provide that?
    Reason for that is because the plan is to use this material in nuclear facility.
    Thanks.

  38. Wahid m. Wahid m. U.A.E. says:

    Is S275JR is equivalent to S355?

  39. Brett Williams Brett Williams South Africa says:

    I've been advised to use 1026 for a suspension system but all I can source in South Africa is S355. Is this equivalent, better, worse?

    Thanks,

    Brett

  40. MOHAMMED MECHERI MOHAMMED MECHERI U.A.E. says:

    How i can select a steel
    1) with low tensile strength and high ductility
    2) High tensile strength and low ductility

  41. ofir benyamin ofir benyamin Israel says:

    Hi,
    what is the approximately yield stress for a S355 STEEL with corrosion, is there any data about it?

  42. LIVINUS HORSFALL LIVINUS HORSFALL Nigeria says:

    cost of beam for anchorage S355 GP EN10248-1

  43. Bryony Coleman Bryony Coleman United Kingdom says:

    I am looking for a UK equivalent to Fe 490-2 to comply with BS EN standard, can you help? please

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of AZoM.com.

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