Material number 1.0503: C45
1.0503 is the European material number (Werkstoffnummer, EN 10027-2) for C45, medium-carbon steel for quenching and tempering specified in EN 10083-2.
Reading 1.0503 digit by digit
An EN 10027-2 number has the form 1.XXYY. The leading 1 marks it as steel. The pair 05 is the steel group, and for this number that group is steels 0.25–0.55 % C or Rm 500–700 MPa. The final pair 03 is a sequential count inside that group and carries no meaning of its own — 1.0503 is simply the 3th entry registered there.
The group digits are the useful part. Reading 05 tells you what kind of steel you are looking at before you know anything else about it, and the 5 other numbers from group 05 held here are listed below.
1.0503 identity card
| Item | Value |
|---|---|
| Material number (EN 10027-2) | 1.0503 |
| Symbolic grade name | C45 |
| Steel group | 05 — steels 0.25–0.55 % C or Rm 500–700 MPa |
| Sequential number in group | 03 |
| Specified in | EN 10083-2 |
| Steel family | Carbon steel |
| Yield, first condition in the table | 340 MPa (+N normalized, ≤ 16 mm) |
| Tensile, same condition | ≥ 620 MPa |
| Cross-references held | 7 grades in 6 systems |
C45 (1.0503) is the 0.45 % carbon steel of EN 10083-2: 305 MPa yield normalized, 490–800 MPa tensile Q&T up to 16 mm. Composition, heat treatment, hardness, 1045/S45C/45# equivalents.
Full data sheet for C45 → · Equivalent grades → · EN 10083-2 →
Group 05 — the neighbouring numbers
| Material number | Grade | Type |
|---|---|---|
| 1.0529 | S350GD | Hot-dip coated structural steel, guaranteed 350 MPa yield — deck and long-span profiles |
| 1.0565 | P355NH | Weldable fine-grain normalized steel for pressure purposes, elevated temperature |
| 1.0570 | St52-3 | General structural steel (DIN 17100, withdrawn) — today S355J2 / S355JR |
| 1.0576 | S355J2H | Non-alloy structural steel for hollow sections, 355 MPa, −20 °C impact |
| 1.0577 | S355J2 | Non-alloy hot-rolled structural steel, −20 °C impact |
Same group digits, so the same broad class of steel. The sequential digits do not rank them.