Steel comes in many different forms and grades. Industries will typically use groups of grades specific for their needs. Common grades of metals used across a range of industries are the structural steel grades such as S355J2+N and S275J0. But what do these numbers and letters mean? To answer this we first need to see the full material grade designation:
BS EN 10025-2 S355J2+N
We will go through each highlighted section in turn:
BS EN 10025-2 = This is the document which contains and specifies the material grade
S = This denotes that the material is a structural steel
355 = An indication of the specified minimum yield strength as measured by a tensile test
J2 = Denotes the quality level of this grade of material and indicates it’s impact properties
+N = Is the final treatment condition of the material
We can now look at some of the common alternatives that are seen in structural steel grades:
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Notation |
Meaning |
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J2 |
Specified charpy impact properties at -20°C |
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J0 |
Specified charpy impact properties at 0°C |
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JR |
Specified charpy impact properties at +23°C (room temperature) |
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K2 |
Specified charpy impact properties at -20°C but with higher minimum values than J2 |
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Notation |
Meaning |
Definition |
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+N |
Normalized rolled |
Final rolling carried out at a temperature to maintain properties after normalizing |
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+AR |
As-rolled condition |
Hot rolled with no subsequent treatment |
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+M |
Thermomechanical rolling |
Thermomechanical rolling can include processes with an increasing cooling rate but cannot include direct quenching and quenching and tempering |
BS EN 10225 materials use a similar system but you will see alternate notations after the numbers for the specified minimum yield strength.
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Notation |
Meaning |
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G |
Grade – under older revisions of this specification grades were just referenced as G and a number i.e. G1, G2 etc. |
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N |
Normalized or normalized rolled steel |
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M |
Thermomechanical rolled steel |
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Q |
Quenched and tempered steel |
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L |
Specified charpy impact properties at -40°C |
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O |
Suitable for offshore structures |
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H |
Hollow section |
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C |
Cold-formed steel |
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HH |
Hot-finished hollow section |
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1 |
No number indicated the charpy impact tests are specified in the longitudinal direction |
ASAMS regularly carries out tests on behalf of clients to ensure that the material they have is the correct grade specified. Please get in touch and we can advise you on the testing required.
References
BS EN 10025-2:2019
BS EN 10225-1,2,3&4:2019