EN 10149-2 S650MC
EN 10149-2 S650MC - High-Strength Thermomechanical Automotive Steel
Detailed material properties of S650MC according to EN 10149-2, including chemical composition, mechanical values, thermal and electrical physical data, international equivalents, and application guidance for cold-formed automotive structural parts.
Cold forming, bending, punching, roll forming, welding, cutting
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EN 10149-2 S650MC Introduction
S650MC is a high-strength low-alloy (HSLA) steel grade defined in EN 10149-2 for hot-rolled flat products intended for cold forming. It is produced via thermomechanical rolling, which refines the grain structure and provides a minimum yield strength of 650 MPa combined with good ductility and excellent bendability.
- Yield strength ≥650 MPa and tensile strength 700–880 MPa across all thicknesses
- Excellent cold formability, allowing complex shapes without cracking
- Used primarily in lightweight automotive structures to reduce weight while maintaining crash performance
- Available as hot-rolled coils, strips, and cut-to-length plates
EN 10149-2 S650MC Chemical Composition
The chemical composition shall conform to the ladle analysis limits of EN 10149-2. The steel is microalloyed with niobium, vanadium, and titanium to achieve high strength and good formability. The sum of Nb+V+Ti is restricted to guarantee consistent properties.
- Carbon is kept low to ensure excellent weldability and toughness.
- Aluminium is added for deoxidation and grain refinement.
| Chemical Element | Standard Value | Remarks |
|---|---|---|
| C | ≤0.12 | Max |
| Si | ≤0.50 | Max |
| Mn | ≤2.00 | Max |
| P | ≤0.025 | Max |
| S | ≤0.010 | Max |
| Al (Total) | ≥0.015 | Min |
| Nb | ≤0.09 | Max |
| V | ≤0.20 | Max |
| Ti | ≤0.15 | Max |
| Nb+V+Ti | ≤0.22 | Microalloy sum max |
EN 10149-2 S650MC Thermal and Electrical Physical Properties
The following physical properties are typical for low-carbon microalloyed structural steels and serve as approximate engineering references. They are not specified in EN 10149-2 but are useful for design calculations.
- Density, elastic moduli, and thermal expansion are similar to general structural steels.
- Values may vary slightly depending on processing and exact composition.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | ~7.85 | g/cm³ | 20 °C |
| Elastic modulus (E) | ~210 | GPa | 20 °C |
| Shear modulus (G) | ~81 | GPa | 20 °C |
| Poisson's ratio (ν) | ~0.3 | — | 20 °C |
| Thermal expansion coefficient (α) | ~11.1 | 10⁻⁶/K | 20 – 100 °C |
| Thermal expansion coefficient (α) | ~12.1 | 10⁻⁶/K | 20 – 200 °C |
| Thermal expansion coefficient (α) | ~12.9 | 10⁻⁶/K | 20 – 300 °C |
| Thermal conductivity (λ) | ~52 | W/(m·K) | 20 °C |
| Specific heat capacity (c) | ~460 | J/(kg·K) | 20 °C |
| Electrical resistivity (ρe) | ~0.13 – 0.25 | 10⁻⁶ Ω·m | 20 °C |
EN 10149-2 S650MC Mechanical Properties
Mechanical properties are determined on transverse test pieces according to EN 10149-2. The values apply to the as-delivered condition. Ductility is given as percentage elongation after fracture using either proportional gauge length (A5) for thickness ≥3 mm or fixed gauge length A80 for thinner material.
- The bend test demonstrates the excellent cold formability.
- Impact toughness is normally not specified but can be agreed upon ordering.
| Property | Required Value | Unit | Test Condition |
|---|---|---|---|
| Yield strength (ReH) | ≥650 | MPa | All thicknesses (t) |
| Tensile strength (Rm) | 700 – 880 | MPa | All thicknesses |
| Elongation after fracture (A80) | ≥12 | % | t < 3 mm, gauge length 80 mm |
| Elongation after fracture (A5) | ≥14 | % | t ≥ 3 mm, proportional gauge length |
| Bend test (180°) | Crack-free at mandrel diameter ≤0.5t | — | t ≤ 8 mm, transverse specimen |
EN 10149-2 S650MC Fully Equivalent Material Standards and Alternative Designations
| Country/Region | Standard | Designation | Remarks |
|---|---|---|---|
| Europe | EN 10149-2 | S650MC | Original standard |
| International (ISO) | ISO 6930-2 | S650MC | Technically identical |
| Germany | DIN EN 10149-2 | S650MC | Adopted European standard |
| United Kingdom | BS EN 10149-2 | S650MC | Adopted European standard |
EN 10149-2 S650MC Application Introduction
S650MC is specifically designed for weight-critical cold-formed structural parts. Its high strength allows reduction of material thickness while maintaining load-bearing and crash-energy absorption capacity.
- Excellent weldability with standard methods (MIG/MAG, resistance welding).
- Suitable for galvanizing without significant loss of strength.
Product Applications: Chassis longitudinal beams and cross members, Reinforcement brackets and impact beams, Suspension control arms and subframes, Seat structures and safety belt components, Lightweight structural profiles
Processed into products: Front and rear bumper reinforcements, B-pillar and roof rail reinforcements, Engine cradle and axle supports, Stamped and roll-formed sections for truck frames, Press-formed parts like wheelhouse stiffeners
Application industries: Automotive (passenger cars, commercial vehicles), Trailer and transport engineering, Construction machinery and agricultural equipment, Railway and wagon manufacturing
EN 10149-2 S650MC Similar or Alternative High-Strength Cold-Forming Steels
| Country/Region | Standard | Designation | Remarks |
|---|---|---|---|
| USA | ASTM A1011/A1011M | HSLAS Grade 100 [690] | Minimum yield 690 MPa; comparable strength, but requires verification of formability and chemistry |
| Japan | JIS G 3135 | SPFC 780Y | Minimum yield 700 MPa; slightly higher strength, good cold formability |
| China | GB/T 20887.1 | HR700/900 | Yield approx. 700 MPa; similar application in automotive structures; detailed equivalence must be confirmed |
| Sweden (commercial) | SSAB | Domex 650 MC | Meets the requirements of EN 10149-2 S650MC; brand-name equivalent |
Notes:
- Optional microalloying with molybdenum (≤0.50 %) and boron (≤0.005 %) may be agreed upon at the time of enquiry and order.
- Improved surface quality conditions such as pickled and oiled are recommended for subsequent cold forming operations.
- Dimensional tolerances are in accordance with EN 10051 for continuously hot-rolled uncoated plate, sheet and strip.
- The steel can be supplied with a test certificate 2.2 or inspection certificate 3.1 per EN 10204.
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