S700MC steel (1.8974): properties, composition, equivalents
S700MC (1.8974): 700 MPa yield, 750–950 MPa tensile, 10–12 % elongation — EN 10149-2 thermomechanical grade for crane booms and trailer chassis. Chemistry (Nb/V/Ti/Mo/B), bend radii, welding rules, A1011 HSLAS Grade 80 and QStE690TM equivalents.
What is S700MC?
S700MC is the strongest grade most cold-forming shops will ever roll: an EN 10149-2 thermomechanically rolled strip with 700 MPa minimum yield and 750–950 MPa tensile, still weldable and bendable at 10–12 % elongation. Werkstoff number 1.8974; QStE690TM in the old German nomenclature, Domex/Strenx 700 MC in the trade. The metallurgy is a very low carbon (≤ 0.12, typically 0.06 %) fine-grained ferrite–bainite matrix strengthened by Ti, Nb, V and Mo precipitates and, in some mills, boron — controlled rolling and accelerated cooling do the rest.
It exists to take weight out of structures: a crane boom, trailer chassis rail or tipper body in S700MC is 40–50 % lighter than the S355 equivalent for the same load, which is payload, fuel and reach. The price is stricter forming rules (bend radius ≥ 1.5–2.5 t, no hot forming, springback compensation), stricter welding heat input, and a fatigue design that respects the higher stresses.
There is no exact ASTM equivalent in A1011 (Grade 80 stops at 550 MPa); SAE J1392 100XF and mill grades cover the US market. For plate above about 12 mm the quenched-and-tempered S690QL (EN 10025-6) is the alternative.
S700MC chemical composition
| Element | Mass % | Note |
|---|---|---|
| C | ≤ 0.12 | |
| Si | ≤ 0.6 | |
| Mn | ≤ 2.1 | |
| P | ≤ 0.025 | |
| S | ≤ 0.015 | |
| Al | ≥ 0.015 | |
| Nb | ≤ 0.09 | |
| V | ≤ 0.2 | |
| Ti | ≤ 0.22 | |
| Mo | ≤ 0.5 | |
| B | ≤ 0.005 |
Ladle analysis, EN 10149-2:2013 Table 1 (S600MC–S700MC). Nb + V + Ti ≤ 0.22 %. Mills typically use C 0.05–0.08, Mn 1.6–2.0, Ti 0.10–0.15 with Nb/Mo/B for precipitation and bainitic strengthening; CEV about 0.35–0.45 despite the low carbon.
S700MC mechanical properties
| Thickness / condition | Yield strength ReH / Rp0.2 MPa (ksi) | Tensile strength Rm MPa (ksi) | Elongation A % | Hardness |
|---|---|---|---|---|
| < 3 mm (A80) | 700 (101.5) | 750–950 (108.8–137.8) | 10 | ≈ 240–290 HB (typ.) |
| ≥ 3 mm (A5) | 700 (101.5) | 750–950 (108.8–137.8) | 12 | — |
| S600MC (for comparison) | 600 (87.0) | 650–820 (94.3–118.9) | 11 / 13 | — |
| S650MC | 650 (94.3) | 700–880 (101.5–127.6) | 10 / 12 | — |
| S900MC | 900 (130.5) | 930–1 200 (134.9–0.1 29.0) | 8 / 10 | — |
| S960MC | 960 (139.2) | 980–1 250 (142.1–0.1 36.3) | 7 / 10 | — |
EN 10149-2:2013 Table 2, longitudinal; A80 for t < 3 mm, A (L0 = 5.65√S0) for t ≥ 3 mm; for t > 8 mm the minimum yield may be 20 MPa lower. Minimum inside bend radius (transverse): S700MC 1.5 t for t ≤ 3 mm, 2.0 t for 3–6 mm, 2.5 t above 6 mm (mill grades such as Strenx 700 MC Plus guarantee tighter).
Impact toughness
S700MC requires a minimum Charpy V-notch energy of 40 J at -20 °C (longitudinal, option). Option in EN 10149-2 (40 J at −20 °C, t ≥ 6 mm); leading mills guarantee 40 J at −40 °C or better.
S700MC equivalent grades
| Grade | System | Match | Why / differences |
|---|---|---|---|
| A1011 HSLAS Grade 80 | ASTM / ASME | Near | ASTM A1011 High-Strength Low-Alloy Grade 80 [550] gives 550 MPa yield / 620 MPa tensile — the highest standard A1011 class; 700 MPa strip in the US is usually sold to mill specifications (e.g. HSLA 100) or SAE J1392 100XF. |
| S650MC | EN (European) | Near | One class lower in EN 10149-2; interchangeable where 650 MPa suffices. |
| Q690 (GB/T 16270 / 1591) | GB/T (China) | Near | Chinese 690 MPa class high-strength structural steel; TM versions for cold forming are mill-specific. |
| SAE J1392 100XF | SAE | Near | SAE J1392 100XF: 690 MPa yield HSLA sheet with improved formability — the automotive-frame equivalent. |
| S690QL | EN (European) | Functional | EN 10025-6 quenched-and-tempered plate with 690 MPa yield: same strength class for heavy plate (> 12 mm), but Q&T instead of TM, larger bend radii and stricter welding. |
| S355MC | 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 S700MC →
Old and superseded designations
| Old name | Standard | Note |
|---|---|---|
| QStE690TM | SEW 092 (withdrawn) | German thermomechanical grade with 690 MPa yield; the direct predecessor. |
| Domex 700 MC / Strenx 700 MC | SSAB trade names | The brand names most buyers use; Strenx 700 MC meets S700MC with tighter bend guarantees. |
Product forms and tolerance standards
Product forms: hot-rolled coil and strip 2–12 mm (+P pickled and oiled usual; to 20 mm from some mills), cut-to-length sheet and plate, slit strip for high-strength tube and profiles.
Dimensional tolerances: thickness/width/flatness: EN 10051, special class common; surface: pickled and oiled; as-rolled on request.
Key property values
S700MC yield strength
≥ 700 MPa (102 ksi) longitudinal; 680 MPa permitted above 8 mm. Typical 730–800 MPa.
S700MC tensile strength
750–950 MPa (109–138 ksi).
S700MC elongation
≥ 10 % (A80, t < 3 mm) / ≥ 12 % (A5, t ≥ 3 mm).
Minimum bend radius (transverse)
1.5 t (t ≤ 3 mm), 2.0 t (3–6 mm), 2.5 t (> 6 mm) per EN 10149-2; mill brands guarantee 1.0–1.5 t. Longitudinal bends: add one step. Expect 10–15° springback.
Impact toughness
Option 40 J at −20 °C (EN); typical mill guarantee 40 J at −40 °C longitudinal.
Physical properties
Density 7.85 g/cm³, E = 210 GPa; hardness about 240–290 HB — cutting tools and punches are sized for it.
Weldability
Weldable with all arc processes; keep heat input low (0.5–1.5 kJ/mm) and interpass ≤ 200 °C so the HAZ does not soften below the base strength — softening of 10–15 % in the HAZ is normal and is allowed for in design. Preheat is generally unnecessary below 12 mm (CEV ≈ 0.40) but hydrogen control (dry consumables, H ≤ 5 ml/100 g) is mandatory. Consumables: matching (G 69 / E 69) for full-strength joints or under-matched (G 46) for better toughness where design allows. Never normalize; PWHT only with the mill's agreement.
Machining, forming and heat treatment
Laser and plasma cutting are routine (edge hardness rises slightly); punching needs 20–30 % more press force than S355 and sharp tools to avoid edge cracks before bending. Press-brake with radius ≥ 1.5–2 t and generous die opening (≥ 10 t); avoid bending across shear-cut edges with burrs. No hot forming above 580 °C.
Typical applications
- Crane, aerial-platform and concrete-pump booms
- Trailer and truck chassis rails, tipper and dump bodies
- Lightweight agricultural and forestry machinery
- Container and rail-wagon frames
- High-strength welded box sections and tube
- Safety and roll-over structures
- Mining and material-handling equipment
Frequently asked questions
What is S700MC used for?
Weight-critical welded structures: crane booms, trailer chassis, tipper bodies, agricultural and mining equipment — anywhere a 700 MPa yield lets the designer halve plate thickness against S355.
Can S700MC be bent?
Yes, that is what the C in MC means, but with radii of at least 1.5–2.5 t (transverse), clean edges and springback compensation. Mill brands such as Strenx 700 MC guarantee tighter radii than the EN minimum.
How is S700MC welded?
Low heat input, hydrogen-controlled consumables, interpass ≤ 200 °C, no normalizing afterwards. Expect a softened HAZ of 10–15 %; use matching 690-class consumables for full-strength joints.
What is the difference between S700MC and S690QL?
Both are 690–700 MPa class. S700MC is thermomechanically rolled strip (to ~12–20 mm) for cold forming, low carbon, cheaper; S690QL (EN 10025-6) is quenched-and-tempered plate to 150 mm with guaranteed −40 °C toughness for heavy structures.
Is there an ASTM equivalent of S700MC?
Not in A1011 (HSLAS Grade 80 stops at 550 MPa yield). SAE J1392 100XF and mill grades (HSLA 100) are the US counterparts; for plate, ASTM A514 (Q&T, 690 MPa) is the functional equivalent.
Why is S700MC not hot formed?
Its strength comes from a fine thermomechanical microstructure and precipitates that dissolve above about 580 °C; hot forming or normalizing drops the yield towards 400 MPa permanently.
Related grades
Verified against EN 10149-2:2013; EN 10149-2:2013 Tables 1–3; EN 10149-1:2013; EN 10051:2010; ASTM A1011/A1011M-23, SAE J1392; EN 10025-6:2019 (for the S690QL comparison). Last checked: September 2026.