Q345GNHLJ Weather Resistant Steel Coil per GB/T 18982-2003
Q345GNHLJ Weather Resistant Steel Coil per GB/T 18982-2003: Composition, Properties & Equivalents
Comprehensive material data for Q345GNHLJ steel coil under GB/T 18982-2003, covering chemical composition, mechanical and thermal properties, international equivalents, and application guidance.
Hot rolling, pickling, optional cold rolling; suitable for welding, bending, roll forming, and stamping
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Q345GNHLJ Weather Resistant Steel Coil per GB/T 18982-2003 Introduction
Q345GNHLJ is a high-strength low-alloy weather-resistant structural steel specified in Chinese standard GB/T 18982-2003 for container manufacturing. With a minimum yield strength of 345 MPa, it exhibits outstanding atmospheric corrosion resistance due to deliberate additions of copper, chromium, and nickel. Over time, the steel forms a dense, adherent patina that self-protects, reducing maintenance needs. The grade suffix 'J' implies enhanced impact toughness requirements, typically at -20 °C. It is mainly supplied in hot-rolled coil, sheet, or plate form and is widely utilized in shipping containers, railway vehicles, and outdoor structures exposed to aggressive environments.
Q345GNHLJ Weather Resistant Steel Coil per GB/T 18982-2003 Chemical Composition
The chemical composition conforms to GB/T 18982-2003 for grade Q345GNHL. The corrosion-protective patina is ensured by alloying with Cu, Cr, and Ni. Low carbon and phosphorus contents, together with microalloying, provide good weldability and low-temperature toughness. The 'L' suffix enforces tighter limits on phosphorus and sulfur for improved toughness.
| Element | Standard Value (wt%) | Remarks |
|---|---|---|
| Carbon (C) | ≤ 0.12 | Maximum |
| Silicon (Si) | 0.20 – 0.50 | Typical range |
| Manganese (Mn) | 0.80 – 1.20 | Higher Mn for strength and toughness |
| Phosphorus (P) | ≤ 0.025 | Maximum; 'L' grade ensures low phosphorus |
| Sulfur (S) | ≤ 0.015 | Maximum |
| Copper (Cu) | 0.25 – 0.55 | Atmospheric corrosion resistance |
| Chromium (Cr) | 0.30 – 1.25 | Atmospheric corrosion resistance |
| Nickel (Ni) | ≤ 0.65 | Enhances toughness and corrosion resistance |
| Titanium (Ti) | ≤ 0.035 | Optional microalloy for grain refinement |
| Nb + V + Ti | ≤ 0.12 | Combined microalloy limit |
Q345GNHLJ Weather Resistant Steel Coil per GB/T 18982-2003 Thermal & Electrical Physical Properties
The following physical properties are typical for low-alloy weathering steels and are not directly specified in GB/T 18982-2003. They are provided for engineering calculations and may vary slightly with exact composition and processing history.
| Property | Typical Value | Unit | Condition / Remarks |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | At 20 °C |
| Modulus of Elasticity (E) | 206 | GPa | At room temperature |
| Shear Modulus (G) | 79.3 | GPa | Calculated |
| Poisson's Ratio (ν) | 0.30 | – | Typical for steels |
| Thermal Expansion Coefficient (α) | 12.0 × 10⁻⁶ | K⁻¹ | Over 20–100 °C |
| Thermal Conductivity (λ) | 45 | W/(m·K) | At room temperature |
| Specific Heat Capacity (c) | 460 | J/(kg·K) | Approximate |
| Electrical Resistivity (ρₑ) | 0.20 × 10⁻⁶ | Ω·m | At 20 °C |
Q345GNHLJ Weather Resistant Steel Coil per GB/T 18982-2003 Mechanical Properties
Mechanical properties are based on GB/T 18982-2003 requirements for Q345GNHL. The 'J' suffix implies guaranteed impact energy, typically at -20 °C. Multiple thickness conditions are shown where values differ. Actual values may be subject to agreement for specific orders.
| Property | Value | Unit | Test Condition / Remarks |
|---|---|---|---|
| Yield Strength (ReH) | ≥ 345 | MPa | Nominal thickness t ≤ 16 mm |
| Yield Strength (ReH) | ≥ 335 | MPa | 16 mm < t ≤ 40 mm |
| Yield Strength (ReH) | ≥ 325 | MPa | 40 mm < t ≤ 63 mm |
| Tensile Strength (Rm) | 470 – 630 | MPa | All thickness ranges |
| Elongation (A) | ≥ 21 | % | Gauge length 50 mm (or proportional); t ≤ 16 mm; for thicker sections, minimum value may be reduced by 1% per 2 mm increase, but not below 17% |
| Bending Test | d = 2a | t ≤ 16 mm, bend angle 180°; d = mandrel diameter, a = specimen thickness | |
| Bending Test | d = 3a | t > 16 mm, bend angle 180° | |
| Impact Energy (KV²) | ≥ 34 | J | At -20 °C, longitudinal specimen; exact test temperature depends on 'J' suffix and contractual agreement |
Q345GNHLJ Weather Resistant Steel Coil per GB/T 18982-2003 Full Equivalent Material Standards and Substitute Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Japan | JIS G3125:2004 | SPA-H | High atmospheric corrosion resisting rolled steel; close match in composition and properties, widely used for containers |
| USA | ASTM A588 / A588M | Grade B | High-strength low-alloy structural steel with enhanced atmospheric corrosion resistance; minimum yield 345 MPa (50 ksi); composition slightly different but functionally equivalent |
| Europe | EN 10025-5:2019 | S355J2W | Weather-resistant structural steel; same minimum yield strength, similar corrosion resistance; may require slight thickness adjustment |
| China | GB/T 4171-2008 | Q355GNH | High weather resistant structural steel; similar corrosion resistance and mechanical properties; often directly interchangeable |
Q345GNHLJ Weather Resistant Steel Coil per GB/T 18982-2003 Application Introduction
Q345GNHLJ steel is specifically engineered for containers and structures exposed to atmospheric corrosion. Its self-protective rust layer often eliminates the need for painting, reducing life‑cycle costs. The material offers excellent formability and reliable weldability, enabling its use in a wide variety of industrial and architectural components.
Product Applications: Shipping containers (dry freight, reefer, tank containers), Railway wagons and hoppers, Truck trailers and semi‑trailers, Prefabricated buildings and modular units, Bridge structural members, Transmission towers and poles
Processed into products: Container panels (side, roof, end walls), Container corner posts and bottom side rails, Wagon side stakes and corrugated sheets, Trailer chassis beams and cross members, Building cladding and support brackets, Cutting edges and wear parts for agricultural implements
Application industries: Container manufacturing (ISO containers, specialized tanks), Railway transport (wagon bodies, underframes), Automotive (trailer frames, cargo bodies), Construction (facades, roofing, bridges), Mining and agricultural equipment (exposed structural parts)
Q345GNHLJ Weather Resistant Steel Coil per GB/T 18982-2003 Similar/Alternative Material Recommendations
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| China | GB/T 18982-2003 | Q345GNH (without L) | Similar corrosion resistance but higher phosphorus/sulfur limits; reduced low‑temperature toughness; suitable where impact is not critical |
| Japan | JIS G3114 | SMA490AW | Hot-rolled atmospheric corrosion resisting steel for welded structures; yield 365 MPa, higher strength; good for heavier sections |
| USA | ASTM A242 | Type 1 | High-strength low-alloy structural steel with atmospheric corrosion resistance; yield 345 MPa; suitable for lighter sections |
| International | ISO 4952:2006 | Fe355W | Weather‑resistant structural steel; similar strength class; verify chemical composition for exact match |
Notes:
The 'J' suffix in the grade designation is likely a customer‑specific requirement for impact testing (temperature and energy) and should be confirmed in the purchase agreement. Surfaced condition (mill edge, slit edge) and coil parameters must be specified. Welding consumables should match the corrosion resistance; low‑hydrogen processes are recommended. For prolonged service in highly aggressive environments (marine, industrial), supplementary coating may be applied. Heat treatment and mechanical properties may vary with thickness.
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