S355MC steel (1.0976): properties, composition, equivalents
S355MC (1.0976) is the EN 10149-2 thermomechanical cold-forming steel: 355 MPa yield, 430–550 MPa tensile, bend radius from 0.5 t, easy welding. Chemistry (Nb/V/Ti), bend table, S420MC–S700MC ladder, A1011 HSLAS-F and QStE380TM equivalents.
What is S355MC?
S355MC is the workhorse of EN 10149-2, the European standard for thermomechanically rolled high-strength steels for cold forming. The designation reads S (structural), 355 (minimum yield, MPa), M (thermomechanical rolling), C (suitable for cold forming). Werkstoff number 1.0976; the old German name QStE380TM and the SSAB trade name Domex 355 MC are still used at the shop floor.
What separates it from ordinary S355J2 is the metallurgy: carbon is held to 0.12 %, sulphur to 0.020 %, and strength comes from niobium/vanadium/titanium micro-alloying plus controlled rolling, giving a fine ferrite grain. The result is a strip that bends to 0.5 t radius in thin gauge without cracking, welds without preheat, and punches cleanly — which is why trailer chassis, truck frames, crane booms, agricultural implements and cold-formed structural profiles are made from it rather than from normalized plate.
The EN 10149-2 ladder runs S315MC → S355MC → S420MC → S460MC → S500MC → S550MC → S600MC → S650MC → S700MC (and S900/S960MC); each step raises yield and tightens the allowable bend radius. ASTM A1011 HSLAS-F Grade 50 and JIS SAPH440 are the sheet equivalents.
S355MC chemical composition
| Element | Mass % | Note |
|---|---|---|
| C | ≤ 0.12 | |
| Si | ≤ 0.5 | |
| Mn | ≤ 1.5 | |
| P | ≤ 0.025 | |
| S | ≤ 0.02 | |
| Al | ≥ 0.015 | |
| Nb | ≤ 0.09 | |
| V | ≤ 0.2 | |
| Ti | ≤ 0.15 |
Ladle analysis, EN 10149-2:2013 Table 1. Fully killed, fine-grain (Al ≥ 0.015 total); Nb + V + Ti ≤ 0.22 %. Low carbon and sulphur are what give the grade its cold-forming and welding behaviour; CEV typically 0.25–0.35.
S355MC mechanical properties
| Thickness / condition | Yield strength ReH / Rp0.2 MPa (ksi) | Tensile strength Rm MPa (ksi) | Elongation A % | Hardness |
|---|---|---|---|---|
| < 3 mm (A80) | 355 (51.5) | 430–550 (62.4–79.8) | 19 | ≈ 130–170 HB (typ.) |
| ≥ 3 mm (A5) | 355 (51.5) | 430–550 (62.4–79.8) | 23 | — |
| S315MC (for comparison) | 315 (45.7) | 390–510 (56.6–74.0) | 20 / 24 | — |
| S420MC | 420 (60.9) | 480–620 (69.6–89.9) | 16 / 19 | — |
| S460MC | 460 (66.7) | 520–670 (75.4–97.2) | 14 / 17 | — |
| S500MC | 500 (72.5) | 550–700 (79.8–101.5) | 12 / 14 | — |
| S600MC | 600 (87.0) | 650–820 (94.3–118.9) | 11 / 13 | — |
| S700MC | 700 (101.5) | 750–950 (108.8–137.8) | 10 / 12 | — |
EN 10149-2:2013 Table 2, longitudinal; A80 for t < 3 mm, A (L0 = 5.65√S0) for t ≥ 3 mm. Transverse tensile allowed up to 20 MPa lower. Minimum inside bend radius (transverse to rolling): S355MC 0.5 t for t ≤ 3 mm, 1.0 t for 3–6 mm, 1.5 t above 6 mm.
Impact toughness
S355MC requires a minimum Charpy V-notch energy of 40 J at -20 °C (longitudinal, option). Impact is an option in EN 10149-2 (40 J at −20 °C longitudinal, 27 J transverse, t ≥ 6 mm); most mills guarantee it on request.
S355MC equivalent grades
| Grade | System | Match | Why / differences |
|---|---|---|---|
| A1011 HSLAS-F Grade 50 | ASTM / ASME | Near | ASTM A1011 High-Strength Low-Alloy with improved Formability, Grade 50 [340]: 340 MPa yield, 410 MPa tensile, inclusion-controlled for bending — the US sheet equivalent. |
| S420MC | EN (European) | Near | Next class in EN 10149-2 (420 MPa) — the usual step up for trailer chassis. |
| S355MC (EN 10149-2) vs S355NC (EN 10149-3) | EN (European) | Near | NC is the normalized-rolled version with the same yield but slightly larger bend radii. |
| Q355 (QStE380TM-type) | GB/T (China) | Near | GB/T 1591 Q355 or the automotive GB/T 3273 grades of 355–380 MPa class. |
| SAPH440 | JIS (Japan) | Near | JIS G3113 hot-rolled automotive structural sheet: yield ≥ 305 MPa, tensile ≥ 440 MPa, good formability. |
| A572 Grade 50 | ASTM / ASME | Functional | Same yield class (345 MPa) as plate/sections, but not thermomechanically rolled and without the guaranteed bend radii. |
| S355J2 | EN (European) | Functional | Normalized/as-rolled structural steel of the same yield; heavier chemistry (C ≤ 0.22), larger bend radii, chosen for plate and sections rather than cold-formed parts. |
| S700MC | EN (European) | Functional | The general cold-forming HSLA grade — roughly half the yield, twice the elongation. |
Identical = same composition and mechanical limits within rounding. Near = one limit differs (e.g. carbon max or impact temperature). Functional = interchangeable for most uses after an engineering check. Full cross-reference for S355MC →
Old and superseded designations
| Old name | Standard | Note |
|---|---|---|
| QStE380TM | SEW 092 (withdrawn) | German thermomechanical HSLA grade; direct predecessor with 380 MPa yield. |
| FeE355TM | EN 10149-2:1995 (draft names) | |
| Domex 355 MC | SSAB trade name | Widely used as a generic term for S355MC in Northern Europe. |
Product forms and tolerance standards
Product forms: hot-rolled coil and strip 1.5–20 mm (+P pickled and oiled usual), cut-to-length sheet and plate to 20 mm, slit strip for roll forming and tube mills.
Dimensional tolerances: thickness/width/flatness: EN 10051 (special class often ordered); surface: as-rolled or pickled; EN 10163 not applicable to strip.
Key property values
S355MC yield strength
≥ 355 MPa (51 ksi), longitudinal, all thicknesses 1.5–20 mm. Typical 380–430 MPa.
S355MC tensile strength
430–550 MPa (62–80 ksi).
S355MC elongation
≥ 19 % (A80, t < 3 mm) / ≥ 23 % (A5, t ≥ 3 mm).
Minimum bend radius (transverse)
0.5 t for t ≤ 3 mm, 1.0 t for 3 < t ≤ 6 mm, 1.5 t for t > 6 mm (EN 10149-2 Table 3). Longitudinal bends may need one step larger.
Impact toughness
Option: 40 J at −20 °C longitudinal (27 J transverse) for t ≥ 6 mm; mills typically supply 40 J at −40 °C on request.
Physical properties
Density 7.85 g/cm³, E = 210 GPa; CEV 0.25–0.35 (very good weldability).
Weldability
Excellent: no preheat up to about 20 mm combined thickness thanks to C ≤ 0.12 and CEV ≈ 0.30. Use consumables matching 355–420 MPa (e.g. G 42 / G 46, E 42); keep heat input moderate (≤ 1.5 kJ/mm on thin gauge) so the fine TM grain is not coarsened in the HAZ. Post-weld heat treatment is not required and normalizing must be avoided — it destroys the TM properties.
Machining, forming and heat treatment
Punching, shearing, laser and plasma cutting are routine and give clean edges suitable for bending without cracking. Cold forming is the purpose of the grade: press braking, roll forming, flanging; keep the bend axis transverse to rolling where radii are tight. Hot forming above 600 °C is not permitted (TM steel).
Typical applications
- Trailer, semi-trailer and truck chassis longitudinal members
- Crane and aerial-platform booms (S355MC–S700MC)
- Agricultural and construction machinery frames and buckets
- Cold-formed structural profiles, C/Z sections and welded box sections
- Tube mills for high-strength structural and mechanical tube
- Automotive wheels, seat frames, brackets
- Racking uprights and mezzanine floors
Frequently asked questions
What is the difference between S355MC and S355J2?
Same 355 MPa yield, different product: S355MC is thermomechanically rolled strip (C ≤ 0.12, Nb/V/Ti) made for cold forming with guaranteed tight bend radii and easy welding; S355J2 is as-rolled or normalized structural plate/sections (C ≤ 0.22) to EN 10025-2. MC must not be normalized or hot-formed.
What does MC mean in S355MC?
M = thermomechanical rolling, C = suitable for cold forming (with specified minimum bend radii). The NC grades of EN 10149-3 are normalized-rolled.
What is the minimum bend radius of S355MC?
0.5 t up to 3 mm, 1.0 t from 3 to 6 mm and 1.5 t above 6 mm, transverse to the rolling direction (EN 10149-2 Table 3).
Is S355MC the same as QStE380TM or Domex 355?
QStE380TM (SEW 092) was the German predecessor with 380 MPa yield; Domex 355 MC is SSAB's brand meeting S355MC. Both are treated as S355MC in practice.
What is the ASTM equivalent of S355MC?
ASTM A1011 HSLAS-F Grade 50 [340] for sheet and strip (340 MPa yield, improved formability); A572 Grade 50 is the plate/section counterpart by yield but without the cold-forming guarantees.
Does S355MC need preheating for welding?
Not up to about 20 mm combined thickness; keep heat input moderate to preserve the fine grain, and never normalize after welding.
Related grades
Verified against EN 10149-2:2013; EN 10149-2:2013 Tables 1–3; EN 10149-1:2013 (general delivery conditions); EN 10051:2010 (tolerances); ASTM A1011/A1011M-23; SEW 092 (historical). Last checked: September 2026.