EN 10025 Designations Decoded: S355J2, S460ML and S235JR

The template

EN 10025 structural steel names follow one template: family letter + yield number + impact code + delivery-condition letters.

• S = structural steel (sibling standards use E for engineering steel, P for pressure purposes, L for line pipe).
• 355 = minimum yield strength in MPa — for the thinnest standard thickness range (≤ 16 mm). The guaranteed yield steps down as thickness rises; the standard table for the ordered product, not the name, gives the value at your thickness.

The impact code: letter plus number

The two-character code states the Charpy impact energy and the temperature at which it is tested:

Code	Impact energy	Test temperature
JR	27 J	+20 °C
J0	27 J	0 °C
J2	27 J	−20 °C
K2	40 J	−20 °C

So S355J2 promises 355 MPa yield with 27 J at −20 °C. A document that just says "S355" without the code is genuinely ambiguous — the impact grade is part of the grade.

Delivery condition letters

• +AR — as rolled (the default, often left unstated).
• N — normalized or normalizing rolled (S355N); NL is the N variant with impact testing at −50 °C.
• M — thermomechanically rolled (TMCP), where strength comes from the rolling schedule and weldability at a given strength is typically better (S460M); ML is the M variant with −50 °C impact.
• Q — quenched and tempered, covered by EN 10025-6 (S690Q); QL tests impact at −40 °C and QL1 at −60 °C.

Decoding S460ML in full: structural steel, 460 MPa minimum yield, thermomechanically rolled, 27 J impact at −50 °C.

Extra suffixes

• W — weathering steel (EN 10025-5: S355J2W).
• H — hollow-section delivery under the EN 10210/10219 route (S355J2H).
• +Z15 / +Z25 / +Z35 — through-thickness quality per EN 10164, specified for welded T- and corner joints at risk of lamellar tearing.
• C — special suitability for cold forming, in the parts of the standard that offer it.

Which part of the standard?

EN 10025-2 covers non-alloy grades (JR/J0/J2/K2), Part 3 normalized fine-grain steels (N/NL), Part 4 TMCP grades (M/ML), Part 5 weathering steels (W) and Part 6 quenched and tempered grades (Q/QL/QL1). The part defines which letters are legal and sets its own chemistry and CEV ceilings: an S355J2 (Part 2) and an S355ML (Part 4) share a yield class but are specified, delivered and certified differently.

Name	Meaning
S235JR	235 MPa yield, 27 J at +20 °C, as rolled
S355J2	355 MPa yield, 27 J at −20 °C
S460ML	460 MPa yield, TMCP, 27 J at −50 °C
S690QL	690 MPa yield, quenched and tempered, impact at −40 °C