EN 10149-2 — Hot rolled flat products made of high yield strength steels for cold forming. Part 2: Thermomechanically rolled steels
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Scope
Thermomechanically rolled (TM) high-strength low-alloy strip, sheet and plate for cold forming: S315MC, S355MC, S420MC, S460MC, S500MC, S550MC, S600MC, S650MC, S700MC, S900MC, S960MC, thickness 1.5–20 mm. Micro-alloyed with Nb, V, Ti; specifies chemistry, yield/tensile/elongation, minimum bend radii and impact (option). Part 3 covers the normalized grades (S260NC–S420NC).
Grades covered by EN 10149-2
| Grade | No. | Type | C % | Yield MPa | Tensile MPa | Nearest equivalents |
|---|---|---|---|---|---|---|
| S355MC | 1.0976 | Thermomechanically rolled HSLA steel for cold forming | ≤ 0.12 | 355 | 430–550 | A1011 HSLAS-F Grade 50, A572 Grade 50, SAPH440 |
| S700MC | 1.8974 | Thermomechanically rolled ultra-high-strength steel for cold forming | ≤ 0.12 | 700 | 750–950 | A1011 HSLAS Grade 80, SAE J1392 100XF, S690QL |
Revision history and superseded standards
| Year | Change |
|---|---|
| 1995 | EN 10149-2:1995 — replaced SEW 092 QStE grades |
| 2013 | EN 10149-2:2013 — current; S900MC and S960MC added |
Supersedes: SEW 092 (QStE 340TM … QStE 690TM); EN 10149-2:1995.
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Related standards
Thermomechanical rolling, and what it forbids
The MC grades — S315MC through S700MC — reach their strength through thermomechanical rolling: a controlled schedule of temperature and deformation that produces a very fine grain at very low carbon, typically under 0.12 %.
That gives an unusual combination — up to 700 MPa yield with a carbon equivalent low enough to weld without preheat in most thicknesses — and it comes with a prohibition. The structure was created by the rolling schedule and cannot be restored by heat treatment. Hot forming, normalising or a long post-weld heat treatment destroys it permanently. Where stress relief is mandatory, the normalised N grades of EN 10149-3 are the correct family.
Bending is the point
These steels exist for cold forming and the standard guarantees it explicitly: a minimum bending radius as a multiple of thickness is tabulated for each grade, transverse and longitudinal.
That guarantee is what separates an MC grade from a structural steel of the same strength. S355MC and S355J2 have similar yield figures; only the first promises to survive a tight bend without cracking. Truck chassis, crane booms, tipper bodies and agricultural equipment are built from MC grades for exactly this reason, and the design saves weight by bending where it would otherwise weld.