Steel grades can look complicated at first glance, but the letters and numbers in a designation such as S355J2+N give important information about a material’s strength, impact performance, and delivery condition. In this guide, we break down what those markings mean and explain some of the most common alternatives used in structural and offshore steels.
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, typically understood in MPa (N/mm²), as measured by a tensile test
J2 – Denotes the quality level of this grade of material and indicates its 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.
|
Notation |
Meaning |
|
J2 |
Specified charpy impact properties at -20°C |
|
J0 |
Specified charpy impact properties at 0°C |
|
JR |
Specified charpy impact properties at +23°C (room temperature) |
|
K2 |
Specified charpy impact properties at -20°C but with higher minimum values than J2 |
|
Notation |
Meaning |
Definition |
|
+N |
Normalised rolled |
Final rolling carried out at a temperature to maintain properties after normalising |
|
+AR |
As-rolled condition |
Hot rolled with no subsequent treatment |
|
+M |
Thermomechanical rolling |
Thermomechanical rolling can include processes with an increasing cooling rate but cannot include direct quenching and quenching and tempering |
Offshore steels follow a similar logic, but use additional notation. BS EN 10225 materials use a similar system but you will see alternate notations after the numbers for the specified minimum yield strength.
|
Notation |
Meaning |
|
G |
Grade – under older revisions of this specification grades were just referenced as G and a number i.e. G1, G2 etc. |
|
N |
Normalised or normalised rolled steel |
|
M |
Thermomechanical rolled steel |
|
Q |
Quenched and tempered steel |
|
L |
Specified Charpy impact properties at -40°C |
|
O |
Suitable for offshore structures |
|
H |
Hollow section |
|
C |
Cold-formed steel |
|
HH |
Hot-finished hollow section |
|
1 |
If no number is shown, the Charpy impact tests are specified in the longitudinal direction. 1 indicates the Charpy impact properties are specified in the transverse direction |
Need to confirm that your material matches the specified grade? ASAMS can help with the testing and verification needed to check compliance with your project requirements. Get in touch with our team to discuss your material, specification and the most suitable testing approach.
References BS EN 10025-2:2019 BS EN 10225-1,2,3&4:2019
