Material number 1.8965: S355J2W
1.8965 is the European material number (Werkstoffnummer, EN 10027-2) for S355J2W, weathering (atmospheric-corrosion-resistant) structural steel, −20 °C impact specified in EN 10025-5.
What 1.8965 means
EN 10027-2 material numbers have the form 1.XXYY: the leading 1 is steel; the next two digits give the steel group (89 → group 89); the last two digits are a sequential number within that group. The number is unique to one composition and survives name changes, which is why 1.8965 has stayed constant while the symbolic name moved from WTSt52-3 to S355J2W.
S355J2W at a glance
S355J2W is the weathering structural steel of EN 10025-5 — the grade Europe buys when the drawing says Corten B (the ArcelorMittal/US Steel trade name) or the old German WTSt52-3. A copper-chromium-nickel addition (Cu 0.25–0.55, Cr 0.40–0.80, Ni ≤ 0.65 %) makes the rust that forms in wet-dry cycles dense and adherent instead of flaky, so an unpainted bridge girder, façade panel, chimney or sculpture stabilises at a 0.1–0.2 mm patina and then corrodes at a tenth of the rate of plain carbon steel. Werkstoff number 1.8965. The mechanical table is that of S355J2: 355 MPa yield, 470–630 MPa tensile, 27 J at −20 °C.
The patina needs alternating wet and dry exposure; permanently damp details, chloride-rich coastal air (> 2 km from the sea is the usual limit), and sheltered crevices do not form it and corrode as ordinary steel. Design details therefore avoid water traps, and run-off is managed because early rust stains concrete and glass. Thin façade sheet (1.5–3 mm) is delivered pre-rusted or blasted; plate for bridges is normally +N.
ASTM A588 Grade A/B is the direct US equivalent; A242 and A606 Type 4 cover the thin, phosphorus-bearing variants (EN S355J2WP); JIS SMA490 and GB Q355NH are the Asian counterparts.
Full data sheet for S355J2W → · Equivalent grades →