QStE380TM Automotive High-Strength Hot-Rolled Steel
QStE380TM Steel – High-Strength Automotive Structural Steel per SEW 092
Detailed data sheet for QStE380TM steel according to SEW 092: chemical composition, mechanical properties, physical properties, and equivalent grades.
Cold forming, bending, stamping, welding, limited machining
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QStE380TM Automotive High-Strength Hot-Rolled Steel Introduction
QStE380TM is a hot-rolled high-strength low-alloy (HSLA) steel grade designed for cold forming, primarily used in automotive structural applications. It is specified under the German standard SEW 092 (now often aligned with DIN EN 10149-2). The steel offers a minimum yield strength of 380 MPa, good weldability, and excellent formability. Typical characteristics include fine-grained microstructure achieved through microalloying with niobium, vanadium, and/or titanium, ensuring consistent mechanical properties and high fatigue resistance. Delivery condition is thermomechanically rolled (TM), which provides improved toughness and dimensional accuracy.
QStE380TM Automotive High-Strength Hot-Rolled Steel Chemical Composition
Typical chemical composition limits according to SEW 092 and common microalloying practice. The steel is aluminium-killed and microalloyed with Nb, V, and/or Ti for grain refinement and precipitation strengthening. The sum of Nb, V, and Ti is typically controlled to a maximum of 0.22%.
| Element | Standard Value (max, unless range) | Remarks |
|---|---|---|
| Carbon (C) | ≤ 0.12% | Ladle analysis |
| Silicon (Si) | ≤ 0.50% | Ladle analysis |
| Manganese (Mn) | ≤ 1.50% | Ladle analysis |
| Phosphorus (P) | ≤ 0.030% | Ladle analysis |
| Sulfur (S) | ≤ 0.025% | Ladle analysis |
| Aluminium (Al) | ≥ 0.015% | Total aluminium, for deoxidation |
| Niobium (Nb) | ≤ 0.09% | Microalloying; typical range 0.02–0.07% |
| Vanadium (V) | ≤ 0.20% | Microalloying; may be present |
| Titanium (Ti) | ≤ 0.22% | Microalloying; typical range 0.005–0.06% |
| Nb+Ti+V | ≤ 0.22% | Sum of microalloying elements |
QStE380TM Automotive High-Strength Hot-Rolled Steel Thermal and Electrical Physical Properties
These physical properties are representative of HSLA steels with similar chemical composition. They may vary slightly with processing conditions and temperature. The data are provided for engineering calculations and are not specified as maximum/minimum values in SEW 092.
| Property | Typical Value | Unit | Test Condition / Remarks |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | At room temperature (20 °C) |
| Modulus of elasticity (E) | 210 | GPa | At room temperature, longitudinal direction |
| Shear modulus (G) | 80.8 | GPa | Calculated from E and ν |
| Poisson's ratio (ν) | 0.3 | - | Elastic range |
| Thermal expansion coefficient (α) | 12.0 | 10⁻⁶/K | For temperature range 20–100 °C |
| Thermal expansion coefficient (α) | 12.5 | 10⁻⁶/K | For temperature range 20–200 °C |
| Thermal expansion coefficient (α) | 13.0 | 10⁻⁶/K | For temperature range 20–300 °C |
| Thermal conductivity (λ) | 50 | W/(m·K) | At room temperature |
| Specific heat capacity | 460 | J/(kg·K) | At room temperature |
| Electrical resistivity (ρe) | 0.15 – 0.25 | µΩ·m | At room temperature, typical range |
QStE380TM Automotive High-Strength Hot-Rolled Steel Mechanical Properties
Minimum mechanical property requirements for transversely oriented test pieces at room temperature. Properties depend on product thickness. The standard specifies upper yield strength (ReH) or 0.2% proof strength (Rp0.2) for yield, and elongation after fracture (A or A80) measured on a gauge length proportional to the specimen. Bending tests are performed with specified former diameters through 180° bending.
| Property | Standard Required Value | Unit | Test Condition / Thickness |
|---|---|---|---|
| Upper yield strength (ReH) | ≥ 380 | MPa | t ≤ 16 mm |
| Upper yield strength (ReH) | ≥ 360 | MPa | 16 mm < t ≤ 25 mm |
| Upper yield strength (ReH) | ≥ 340 | MPa | 25 mm < t ≤ 40 mm |
| Tensile strength (Rm) | 450 – 590 | MPa | t ≤ 16 mm |
| Tensile strength (Rm) | 440 – 580 | MPa | 16 mm < t ≤ 40 mm |
| Percentage elongation after fracture (A80) | ≥ 19 | % | t ≤ 3 mm (gauge length 80 mm) |
| Percentage elongation after fracture (A) | ≥ 23 | % | t > 3 mm (gauge length 5.65√S₀) |
| Bending test (180°) | Former dia. = 0.5 t | - | t ≤ 12 mm |
QStE380TM Automotive High-Strength Hot-Rolled Steel Full Equivalent Grades – Standards and Replaceable Designations
| Country / Region | Standard | Grade | Remarks |
|---|---|---|---|
| Germany | SEW 092 | QStE380TM | Original grade |
| European Union | EN 10149-2:2013 | S380MC | Direct equivalent, thermomechanically rolled |
| International | ISO 4950-2:1995 | S380MC | Equivalent for high yield strength flat products |
| Italy | UNI EN 10149-2 | S380MC | National adoption |
| France | NF EN 10149-2 | S380MC | National adoption |
| United Kingdom | BS EN 10149-2 | S380MC | National adoption |
| Spain | UNE EN 10149-2 | S380MC | National adoption |
QStE380TM Automotive High-Strength Hot-Rolled Steel Application Introduction
QStE380TM is designed for structural parts requiring high strength, good cold formability, and reliable weldability. It is typically used in as-delivered (thermomechanically rolled) condition without subsequent heat treatment. The steel can be bent, cut, stamped, and welded using standard methods. Preheating is usually not necessary for light gauge material.
Product Applications: Vehicle chassis and subframes, Longitudinal and cross members for trucks, Wheel rims and discs, Cold-formed sections and profiles, Reinforcement brackets and crash boxes, Suspension components (control arms, spring brackets), Pick-up truck beds and frames, Bus frames and structural elements
Processed into products: Side rails and frame rails, Crossmembers, engine cradles, Seat structures and backrest frames, Bumper reinforcements and energy-absorbing parts, Axle housings and suspension arms, Transmission support brackets, Agricultural implement arms and hitches
Application industries: Automotive (passenger cars and commercial vehicles), Transportation and trailer manufacturing, Agricultural machinery, Construction and earth-moving equipment, General engineering (frames, supports, containers)
QStE380TM Automotive High-Strength Hot-Rolled Steel Similar / Nearby Alternative Grades
| Country / Region | Standard | Grade | Remarks |
|---|---|---|---|
| European Union | EN 10149-2 | S355MC | Lower minimum yield strength (355 MPa); similar formability; often interchangeable for less demanding applications |
| European Union | EN 10149-2 | S420MC | Higher minimum yield strength (420 MPa); slightly lower elongation; good for upgrading strength without thickness increase |
| Germany | SEW 092 | QStE340TM | Lower strength variant (340 MPa min); better formability |
| Germany | SEW 092 | QStE420TM | Higher strength variant (420 MPa min); reduced formability |
| China | GB/T 20887.1 | HR380F | High formability hot-rolled strip; comparable strength but different chemical approach |
| Japan | JIS G 3134 | SPFH 380 | Hot-rolled high-strength steel sheet for automobile structural use; similar yield class |
Notes:
- The material is typically supplied with a pickled and oiled surface for improved forming and corrosion protection.
- Impact toughness requirements are not mandatory in SEW 092 but may be agreed upon; typical Charpy V-notch values at -20 °C are ≥ 27 J for longitudinal specimens.
- For welding, low carbon equivalent (CEV) ensures good weldability without preheating for thicknesses up to approx. 15 mm; matching filler metals are recommended.
- Galvanizing (hot-dip) is possible with appropriate post-rolling control of silicon content.
- Dimensional tolerances comply with EN 10051 or relevant product standards.
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