Q/BQB 310 QST500TM Hot Rolled Steel Coil
Q/BQB 310 QST500TM Hot Rolled Steel Coil: High-Strength Structural Steel for Cold Forming
Comprehensive data on QST500TM hot rolled steel coil, including chemical composition, mechanical properties, thermal and electrical physical properties, international equivalents, and application guide.
Thermomechanical rolling, cold forming, bending, welding, machining
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Q/BQB 310 QST500TM Hot Rolled Steel Coil Introduction
QST500TM is a high-strength, thermomechanically rolled structural steel defined under Q/BQB 310-2009 (Baosteel) and originally influenced by SEW 092 (German Iron and Steel Specification). It is a fine-grained steel designed for cold forming, delivering a minimum yield strength of 500 MPa with excellent weldability and good toughness. The "TM" designation indicates thermomechanical rolling, which provides superior mechanical properties without the need for subsequent heat treatment. Typical applications include structural components in automotive, crane, and construction industries. The material is supplied as hot rolled coil or cut sheet in the as-rolled condition.
Q/BQB 310 QST500TM Hot Rolled Steel Coil Chemical Composition
The chemical composition of QST500TM is controlled to achieve fine grain structure and high strength via microalloying elements such as niobium, vanadium, and titanium. Low carbon equivalent ensures excellent weldability. The values below represent ladle analysis limits per Q/BQB 310 and SEW 092. Single values are maximum unless otherwise specified.
| Element | Standard Value (max %) | Remarks |
|---|---|---|
| Carbon (C) | ≤0.12 | |
| Silicon (Si) | ≤0.50 | |
| Manganese (Mn) | ≤1.70 | |
| Phosphorus (P) | ≤0.025 | |
| Sulfur (S) | ≤0.015 | |
| Aluminum (Al total) | ≥0.015 | Minimum content required for grain refinement |
| Niobium (Nb) | ≤0.09 | Grain refining element |
| Vanadium (V) | ≤0.20 | Microalloying element |
| Titanium (Ti) | ≤0.15 | Microalloying element |
| Molybdenum (Mo) | ≤0.50 | Optional for strength adjustment |
| Boron (B) | ≤0.005 | Optional microalloying |
Q/BQB 310 QST500TM Hot Rolled Steel Coil Thermal and Electrical Physical Properties
Physical properties are typical for HSLA steel at ambient temperature unless otherwise specified. These values are suitable for engineering design calculations but are not guaranteed minimums. They are derived from published data for comparable microalloyed steels.
| Property | Standard Value | Unit | Test Condition / Remarks |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | At 20 °C |
| Modulus of Elasticity (E) | 210 | GPa | At 20 °C |
| Shear Modulus (G) | 81 | GPa | At 20 °C |
| Poisson's Ratio (ν) | 0.3 | - | Elastic range |
| Thermal Expansion Coefficient (α) | 12 × 10⁻⁶ | K⁻¹ | Mean between 20 °C and 100 °C |
| Thermal Expansion Coefficient (α) | 12.5 × 10⁻⁶ | K⁻¹ | Mean between 20 °C and 300 °C |
| Thermal Conductivity (λ) | 50 | W/(m·K) | At 20 °C |
| Thermal Conductivity (λ) | 44 | W/(m·K) | At 200 °C |
| Specific Heat Capacity (c) | 460 | J/(kg·K) | At 20 °C |
| Electrical Resistivity (ρ_e) | 2.5 × 10⁻⁷ | Ω·m | At 20 °C |
Q/BQB 310 QST500TM Hot Rolled Steel Coil Mechanical Properties
Mechanical properties are determined on test pieces taken transversely to the rolling direction, with thermomechanically rolled condition, at room temperature. Yield strength and tensile strength depend on product thickness; values below are for thickness ≤8 mm unless noted. Impact test values are for longitudinal specimens at specified temperature.
| Property | Standard Requirement | Unit | Test Condition |
|---|---|---|---|
| Upper Yield Strength (ReH) | ≥500 | MPa | Ambient; thickness ≤3 mm |
| Upper Yield Strength (ReH) | ≥500 | MPa | Ambient; thickness 3-8 mm |
| Tensile Strength (Rm) | 550 - 700 | MPa | Ambient; all thickness |
| Elongation after fracture (A80) | ≥12 | % | Gauge length 80 mm, thickness ≤3 mm |
| Elongation after fracture (A5) | ≥14 | % | Gauge length proportional, thickness >3 mm |
| Total Elongation under Force (Agt) | ≥10 | % | Ambient; typical value for reference |
| Bend Test (Mandrel Diameter) | ≤1.5 t | - | 180° bend, t=specimen thickness |
| Charpy Impact (KV) at -20°C | ≥40 | J | Longitudinal V-notch specimen |
| Charpy Impact (KV) at 0°C | ≥40 | J | Longitudinal V-notch specimen |
| Strain hardening exponent (n50-80) | ≥0.13 | - | Indicative; for thickness ≤3 mm |
Q/BQB 310 QST500TM Hot Rolled Steel Coil Complete Equivalent Material Standards and Designations
The following standards and grades are considered technically identical and can be substituted for QST500TM in most applications, subject to customer specification.
| Country / Region | Standard | Grade | Remarks |
|---|---|---|---|
| Europe | EN 10149-2:2013 | S500MC | Thermomechanically rolled cold forming steel |
| International (ISO) | ISO 6930-2:2018 | FeE500TM | High yield strength, thermomechanically rolled |
| China | GB/T 20887.4-2022 | S500MC | Consistent with EN standard |
| Germany | DIN EN 10149-2 | S500MC | Adopting European standard |
Q/BQB 310 QST500TM Hot Rolled Steel Coil Application Introduction
QST500TM is primarily employed in structural parts that demand high strength with excellent cold formability and weldability. Its fine grain structure ensures good toughness at low temperatures. Due to its thermomechanical rolling process, the steel exhibits consistent quality suitable for high-volume production and robotic welding. Key application areas include:
Product Applications: Truck chassis side members and cross members, Crane telescopic booms and outriggers, Trailer and tipper body frames, Cold-formed structural hollow sections, Earthmoving equipment frames and buckets
Processed into products: Longitudinal beams, mounting brackets, reinforcement plates, Suspension parts, spring seats, torsion bars, Stamped and formed wheel rims, Boom extensions, luffing frames, Bent profiles, structural angles and channels
Application industries: Automotive and commercial vehicles, Material handling and lifting equipment, Agricultural machinery, Construction and building structures, Railway wagons and infrastructure, General engineering and pressure vessels
Q/BQB 310 QST500TM Hot Rolled Steel Coil Materials with Similar Properties
The following materials offer similar strength levels and may be used as alternatives, but always require confirmation of chemical and mechanical requirements according to the applicable standard.
| Country / Region | Standard | Grade | Remarks |
|---|---|---|---|
| Europe | EN 10149-2 | S550MC | Higher minimum yield strength (550 MPa), lower elongation |
| Europe | EN 10149-2 | S460MC | Lower yield strength (460 MPa), higher ductility |
| China | GB/T 20887.4 | S550MC | Similar to EN S550MC |
| USA | ASTM A1011/A1011M | Grade 80 [550] | Similar strength, different alloy philosophy |
| Japan | JIS G3134 | SPFH590Y | Automotive hot rolled high strength steel |
Notes:
Additional Information:
- The steel can be supplied with specific controlled surface quality and oiled for improved processing.
- For structural applications subject to static loads, design strengths can be taken as the minimum yield with a safety factor per applicable codes.
- Weldability is excellent with common methods like MAG, plasma, and spot welding; preheating is not required up to 30 mm thickness.
- Due to the microalloyed chemistry, hot-dip galvanizing (zinc) is possible without significant property degradation.
- Bake-hardening after forming can provide additional strength improvement for automotive parts.
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