EN 10025, 10088, 10083 … with Werkstoff numbers (1.xxxx). Issued by CEN. 34 grades and 16 standards are documented so far; each grade links to a full data sheet and a graded cross-reference to the other systems.
EN names come in two parallel forms and both appear on certificates. The name describes the steel — S355J2 is a structural grade with 355 MPa yield tested at −20 °C. The number (Werkstoffnummer) identifies it — 1.0577 is the same steel in EN 10027-2 form.
The name convention differs by purpose. Structural and pressure grades put the property first: S for structural, P for pressure, L for line pipe, E for engineering, followed by the yield in MPa. Alloy and tool grades put the chemistry first: the carbon in hundredths of a per cent, then the alloying elements with multiplier-coded contents. Stainless grades use an X prefix followed by carbon and the alloy list — X5CrNi18-10 is 0.05 % carbon with 18 % chromium and 10 % nickel.
Reading the Werkstoff number
The 1.xxxx number is not arbitrary. The leading 1 means steel. The next two digits are the material group: 1.00–1.09 unalloyed base and quality steels, 1.10–1.19 unalloyed special steels, 1.20–1.29 tool steels, 1.40–1.49 stainless and heat-resisting, 1.5x–1.8x the alloy structural families.
So 1.4301 is immediately recognisable as stainless before you know it is 304, and 1.2379 as a tool steel. The last two digits are a serial number with no further meaning.
Why the number and the name both survive
The name carries information a buyer can act on; the number is unambiguous. "Stainless 18/10" describes several grades, but 1.4301 is exactly one. Certificates carry both, and an order that gives both is the least likely to be misread.
This matters most where the name is nearly identical across grades. X5CrNi18-10 and X2CrNi18-9 differ by one digit in the name and by 1.4301 against 1.4307 in the number — and by whether they can be welded thick without sensitising.
faq.h
What does S355J2 mean?
S is a structural steel, 355 is the guaranteed minimum yield strength in MPa for the thinnest thickness band, and J2 means the steel must absorb 27 joules in a Charpy impact test at −20 °C.
What is a Werkstoff number?
The EN 10027-2 material number, written 1.xxxx. The leading 1 means steel, the next two digits give the material group — 1.4xxx is stainless, 1.2xxx tool steel, 1.0xxx unalloyed — and the last two are a serial number.
What does the X mean in X5CrNi18-10?
X marks a high-alloy steel, where total alloying exceeds 5 %. The 5 is carbon in hundredths of a per cent, and the numbers after the element symbols are the actual percentages — 18 % chromium, 10 % nickel.
How do I read 42CrMo4?
0.42 % carbon, chromium as the principal alloying element. The 4 is divided by the element factor — 4 for Cr, Mn, Ni, Si, Co and W — giving 1 % chromium. Molybdenum is present but below the level that earns its own number.
Which EN standard covers structural steel?
EN 10025 in six parts: part 2 for non-alloy structural steels (S235 to S355), part 3 for normalised weldable fine grain, part 4 for thermomechanically rolled, part 5 for weathering steels and part 6 for quenched and tempered plate.