B420CL Hot Rolled Steel Coil
B420CL Hot Rolled Steel Coil: Low-Alloy High-Strength for Cold Forming (Q/BQB 310-2009)
Detailed material data for B420CL hot rolled steel coil under Baosteel standard Q/BQB 310-2009, including chemical composition, mechanical and physical properties, international equivalents, and applications.
Cold forming, bending, stamping, flanging, roll forming, welding
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B420CL Hot Rolled Steel Coil Introduction
B420CL is a low-alloy high-strength hot rolled steel grade under Baosteel enterprise standard Q/BQB 310-2009, designed for cold forming applications. It offers a minimum tensile strength of 420 MPa with excellent formability and weldability. The steel is microalloyed with niobium, vanadium, or titanium to achieve grain refinement and precipitation strengthening. Typical supply condition is hot rolled coil/plate with controlled rolling and cooling, suitable for direct cold forming without annealing. It is widely used in automotive structural and chassis components requiring high strength and good fatigue performance.
B420CL Hot Rolled Steel Coil Chemical Composition
The chemical composition of B420CL is designed for excellent cold formability and high strength. The steel is microalloyed with Nb, V, and/or Ti to achieve the required mechanical properties through grain refinement and precipitation hardening. The limits are as per Q/BQB 310-2009 standard.
| Chemical Element | Standard Value (wt%) | Remark |
|---|---|---|
| Carbon (C) | ≤ 0.12 | Max allowable for weldability |
| Silicon (Si) | ≤ 0.50 | |
| Manganese (Mn) | ≤ 1.50 | Depending on thickness |
| Phosphorus (P) | ≤ 0.030 | |
| Sulfur (S) | ≤ 0.025 | |
| Aluminum (Alt) | ≥ 0.015 | Total aluminum, for deoxidation |
| Niobium (Nb) | ≤ 0.09 | Optional microalloy element |
| Vanadium (V) | ≤ 0.20 | Optional microalloy element |
| Titanium (Ti) | ≤ 0.22 | Optional microalloy element |
| Nitrogen (N) | ≤ 0.012 | If not bound by Ti |
| Copper (Cu) | ≤ 0.30 | Residual |
| Chromium (Cr) | ≤ 0.30 | Residual |
| Nickel (Ni) | ≤ 0.30 | Residual |
| Molybdenum (Mo) | ≤ 0.10 | Residual |
| Combination Nb+V+Ti | ≤ 0.22 | For grain refinement and strength |
B420CL Hot Rolled Steel Coil Thermal and Electrical Physical Properties
Physical properties are typical for low-alloy structural steel and are not part of the delivery specification. They are provided for design calculations and processing guidance.
| Property | Standard Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | At 20 °C |
| Elastic modulus (E) | ≈ 210 | GPa | At room temperature |
| Shear modulus (G) | ≈ 80 | GPa | At room temperature |
| Poisson's ratio (ν) | 0.3 | - | Elastic range |
| Thermal expansion coefficient (α) | 12.0 × 10⁻⁶ | K⁻¹ | 20-100 °C |
| Thermal expansion coefficient (α) | 12.8 × 10⁻⁶ | K⁻¹ | 20-200 °C |
| Thermal expansion coefficient (α) | 13.5 × 10⁻⁶ | K⁻¹ | 20-300 °C |
| Thermal conductivity (λ) | ~ 50 | W/(m·K) | At 20 °C |
| Specific heat capacity (cp) | ~ 460 | J/(kg·K) | At 20 °C |
| Electrical resistivity (ρ_e) | ~ 0.20 × 10⁻⁶ | Ω·m | At 20 °C |
B420CL Hot Rolled Steel Coil Mechanical Properties
Tensile and yield properties are tested on transverse specimens in accordance with Q/BQB 310. The values vary slightly depending on the product thickness. The steel is characterized by high strength and good ductility for cold forming operations.
| Property | Required Value | Unit | Test Condition |
|---|---|---|---|
| Upper yield strength (ReH) | ≥ 305 | MPa | Thickness ≤ 3.0 mm |
| Upper yield strength (ReH) | ≥ 315 | MPa | Thickness 3.0-6.0 mm |
| Tensile strength (Rm) | 420 - 540 | MPa | All thicknesses |
| Elongation after fracture (A80mm) | ≥ 20 | % | Thickness 1.6-2.0 mm |
| Elongation after fracture (A80mm) | ≥ 21 | % | Thickness 2.0-2.5 mm |
| Elongation after fracture (A80mm) | ≥ 22 | % | Thickness 2.5-3.0 mm |
| Elongation after fracture (A5.65√S0) | ≥ 24 | % | Longitudinal, typical |
| Bending test (bend angle 180°) | Crack-free | - | Bend diameter = 0.5 × sheet thickness (t) for t ≤ 3 mm, = 1.0 × t for t > 3 mm (recommended) |
| Impact energy (KV) | Not specified | J | Room temperature, optional test |
B420CL Hot Rolled Steel Coil Direct Equivalent Standards and Replaceable Grades
| Country/Region | Standard | Grade | Remark |
|---|---|---|---|
| Europe | EN 10149-2:1996 | S420MC | Closest equivalent; similar chemical and mechanical properties; microalloyed steel for cold forming |
| Japan | JIS G 3134:2018 | SPFH540 | Tensile strength min. 540 MPa; yield strength may differ; comparable formability |
| International | ISO 6930-1:2004 | FeE420 | High yield strength steel for cold forming; microalloyed |
| China | GB/T 20887.1-2007 | HR 420MC | Chinese national standard equivalent to S420MC; closely matches B420CL |
B420CL Hot Rolled Steel Coil Application Introduction
B420CL steel is optimized for cold forming of structural components in the automotive industry. Its high strength reduces weight while maintaining crashworthiness and durability. It can replace traditional mild steels in many applications, allowing thickness reduction and fuel efficiency improvement. The material is suitable for forming processes such as bending, punching, roll forming, and deep drawing to a limited extent. Welding is possible with conventional methods (MIG/MAG, spot welding) without preheating.
Product Applications: Automotive chassis and subframes, Wheel rims and disc wheels, Longitudinal and cross members of truck frames, Suspension control arms and brackets, Bumpers and crash boxes, Engine mounts and support structures, Agricultural equipment frames, Roll-formed profiles for construction
Processed into products: Automobile wheel spokes and rims, Front/rear longitudinal beams, Cross member reinforcements, Suspension coil spring seats, Control arms (stamped and welded), Subframe components, Trailer frame rails, Reinforcement brackets for body-in-white
Application industries: Automotive manufacturing (passenger cars, commercial vehicles), Transportation and trailer industry, Agricultural machinery, Construction machinery (light to medium structural parts), General engineering and metal processing
B420CL Hot Rolled Steel Coil Similar Alternative Materials
| Country/Region | Standard | Grade | Remark |
|---|---|---|---|
| Japan | JIS G 3113 | SAPH440 | Hot rolled automobile structural steel; slightly lower tensile strength (min. 440 MPa); good formability |
| Europe | EN 10149-2 | S460MC | Higher strength grade (min. 460 MPa yield), still cold formable; can be substituted if higher strength needed |
| Europe | SEW 092 | QStE420TM | Thermomechanically rolled steel with min. tensile 420 MPa; similar to B420CL but delivery condition differs |
| USA | SAE J1392 | 050XK | High strength low alloy steel with min. tensile 420 MPa; approximate match |
Notes:
Processing Note: B420CL is delivered in the hot-rolled condition. For complex forming, a skin pass may improve surface quality and formability. The steel exhibits a fine-grained ferrite-pearlite microstructure with microalloy precipitates. Surface protection: For corrosive environments, subsequent galvanizing or painting is recommended. Thickness tolerance: Conforms to Q/BQB 301 or EN 10051. Mechanical properties may degrade slightly after severe cold forming; if post-forming strength is critical, consider a stress relief annealing at 550°C.
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