GB/T 4171 Q460NH Weather Resistant Steel Plate
GB/T 4171 Q460NH Weather Resistant Steel Plate - High-Strength Atmospheric Corrosion Resistant Steel
Q460NH is a high-strength atmospheric corrosion resistant structural steel specified in Chinese standard GB/T 4171. It develops a protective patina for extended service life in outdoor environments without painting.
Hot rolling, cold forming, welding, cutting, machining
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GB/T 4171 Q460NH Weather Resistant Steel Plate Introduction
Q460NH weather resistant steel plate, governed by GB/T 4171, is a high-strength low-alloy structural steel designed for superior resistance to atmospheric corrosion. By adding alloying elements such as copper, chromium, and nickel, a dense, adherent oxide layer (patina) forms on the surface, significantly slowing further corrosion and eliminating the need for protective coatings in many applications. With a minimum yield strength of 460 MPa, it provides excellent structural integrity while reducing maintenance costs.
- Excellent corrosion resistance in unpainted conditions
- High strength-to-weight ratio
- Good weldability and formability
- Long-term durability in harsh weather
Typical applications include bridges, building structures, railway vehicles, containers, and towers.
GB/T 4171 Q460NH Weather Resistant Steel Plate Chemical Composition
The chemical composition of Q460NH in accordance with GB/T 4171-2008 is presented below. Alloying elements like Cu, Cr, and Ni provide atmospheric corrosion resistance. Residual elements P and S are strictly controlled. Microalloying with Nb, V, Ti may be added for grain refinement and strengthening, but must be within the allowed limits.
| Element | Standard Value | Remarks |
|---|---|---|
| Carbon (C) | ≤0.12 | Max 0.12% |
| Silicon (Si) | ≤0.50 | |
| Manganese (Mn) | ≤1.00 | |
| Phosphorus (P) | ≤0.020 | |
| Sulfur (S) | ≤0.015 | |
| Copper (Cu) | 0.20 - 0.55 | Essential for weather resistance |
| Chromium (Cr) | 0.30 - 1.25 | Enhances patina formation |
| Nickel (Ni) | ≤0.65 | Improves toughness and corrosion resistance |
| Niobium (Nb) | ≤0.060 | Grain refiner, optional |
| Vanadium (V) | ≤0.12 | Optional microalloying |
| Titanium (Ti) | ≤0.10 | Optional microalloying |
| Aluminum (Al) | ≥0.020 | For deoxidation, if added |
| Nitrogen (N) | ≤0.012 | Max |
GB/T 4171 Q460NH Weather Resistant Steel Plate Thermal and Electrical Physical Properties
The physical properties below are typical values for Q460NH weather resistant steel at room temperature, based on general data for low-alloy weathering steels. These are not specified in GB/T 4171 but are provided for engineering reference. Slight variations may occur depending on exact chemical composition and heat treatment.
| Property | Typical Value | Unit | Test Condition / Remarks |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | At 20 °C |
| Modulus of Elasticity (E) | 200 - 210 | GPa | At 20 °C |
| Shear Modulus (G) | 79 - 81 | GPa | At 20 °C |
| Poisson's Ratio (ν) | 0.3 | - | At 20 °C |
| Thermal Expansion Coefficient (α) | 11.0 - 12.0 | µm/(m·K) | 20 °C to 100 °C |
| Thermal Conductivity (λ) | 30 - 40 | W/(m·K) | At 20 °C |
| Specific Heat Capacity | 450 - 490 | J/(kg·K) | At 20 °C |
| Electrical Resistivity (ρ_e) | 0.18 - 0.25 | µΩ·m | At 20 °C |
GB/T 4171 Q460NH Weather Resistant Steel Plate Mechanical Properties
The following mechanical properties are minimum required values according to GB/T 4171 for Q460NH in the as-delivered condition, depending on plate thickness. Test specimen orientation is transverse.
- Yield strength (ReH) is valid for thicknesses up to 150 mm.
- Tensile strength (Rm) and elongation (A) after fracture are tested on standard round or flat specimens.
- Charpy impact energy (KV) is determined at 0°C for standard V-notch specimens.
| Property | Specified Value | Unit | Test Condition / Thickness Range |
|---|---|---|---|
| Yield Strength (ReH) | ≥460 | MPa | t ≤ 16 mm |
| Yield Strength (ReH) | ≥450 | MPa | 16 mm < t ≤ 40 mm |
| Yield Strength (ReH) | ≥440 | MPa | 40 mm < t ≤ 63 mm |
| Yield Strength (ReH) | ≥430 | MPa | 63 mm < t ≤ 80 mm |
| Yield Strength (ReH) | ≥420 | MPa | 80 mm < t ≤ 100 mm |
| Yield Strength (ReH) | ≥410 | MPa | 100 mm < t ≤ 150 mm |
| Tensile Strength (Rm) | 570 - 730 | MPa | t ≤ 16 mm |
| Tensile Strength (Rm) | 560 - 720 | MPa | 16 mm < t ≤ 40 mm |
| Tensile Strength (Rm) | 550 - 710 | MPa | 40 mm < t ≤ 63 mm |
| Tensile Strength (Rm) | 540 - 700 | MPa | 63 mm < t ≤ 80 mm |
| Tensile Strength (Rm) | 530 - 690 | MPa | 80 mm < t ≤ 100 mm |
| Tensile Strength (Rm) | 520 - 680 | MPa | 100 mm < t ≤ 150 mm |
| Elongation after fracture (A) | ≥15 | % | L0=5.65√S0, transverse, t ≤ 16 mm |
| Elongation after fracture (A) | ≥15 | % | L0=5.65√S0, transverse, 16 mm < t ≤ 40 mm |
| Elongation after fracture (A) | ≥14 | % | L0=5.65√S0, transverse, 40 mm < t ≤ 63 mm |
| Elongation after fracture (A) | ≥14 | % | L0=5.65√S0, transverse, 63 mm < t ≤ 80 mm |
| Elongation after fracture (A) | ≥14 | % | L0=5.65√S0, transverse, 80 mm < t ≤ 100 mm |
| Elongation after fracture (A) | ≥14 | % | L0=5.65√S0, transverse, 100 mm < t ≤ 150 mm |
| Impact Energy (KV) | ≥47 | J | 0°C, V-notch, longitudinal |
| Impact Energy (KV) | ≥27 | J | 0°C, V-notch, transverse |
GB/T 4171 Q460NH Weather Resistant Steel Plate Full Equivalent Material Standards and Alternative Grade Recommendations
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Europe | EN 10025-5:2019 | S460W (1.8957) | Closest fully equivalent weathering steel grade with minimum yield 460 MPa, similar chemistry and corrosion class. |
| Germany | DIN EN 10025-5 | S460W | Identical to European standard. |
| UK | BS EN 10025-5 | S460W | Identical to European standard. |
| France | NF EN 10025-5 | S460W | Identical to European standard. |
| Italy | UNI EN 10025-5 | S460W | Identical to European standard. |
| Spain | UNE EN 10025-5 | S460W | Identical to European standard. |
GB/T 4171 Q460NH Weather Resistant Steel Plate Application Introduction
Q460NH weather resistant steel is ideal for structures exposed to the atmosphere without protective coatings, relying on a naturally formed stable oxide layer for corrosion protection. It is widely used in civil engineering, transportation, and industrial facilities.
Product Applications: Unpainted steel bridges, High-rise building frames, Freight train carriages and hopper cars, Shipping containers, Highway guardrails and sign supports, Chimney stacks and flue ducts, Sculptures and architectural cladding
Processed into products: Bridge girders, diaphragms, and stiffeners, Welded beams and columns for building frames, Railcar side frames, bolsters, and end structures, Container corner castings, side plates, and roof panels, Transmission tower legs, cross-arms, and bracings, Boom and chassis components of excavators and cranes, Exhaust stacks, ducting, and air preheater casings
Application industries: Bridge engineering, Architectural and structural engineering, Railway vehicle manufacturing, Container and shipbuilding (for non-marine atmospheres), Power transmission towers and poles, Mining and earthmoving equipment, Offshore structural components
GB/T 4171 Q460NH Weather Resistant Steel Plate Similar / Alternative Weather Resistant Steel Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Japan | JIS G3114:2004 | SMA570W | Hot-rolled atmospheric corrosion resisting steel for welded structure; yield ≥460 MPa for thickness ≤40 mm, higher Ni content, close welding performance. |
| USA | ASTM A588/A588M | Grade E | High-strength low-alloy weathering steel; min yield 345 MPa (50 ksi) up to 100 mm, but 460 MPa class requires thicker sections; strength slightly lower but equivalent corrosion resistance. |
| USA | ASTM A242/A242M | Type 1 | Weathering steel with min yield 345 MPa (50 ksi), lower strength but similar corrosion resistance. |
| International | ISO 4952:2003 | Fe510W (S460W) | Weather resistant steel with minimum yield 460 MPa, similar composition and properties; directly corresponding to EN S460W. |
| Russia | GOST 19281-89 | 16G2AFD | Low-alloy steel with added Cu, Cr for weather resistance, approximate yield >440 MPa, not identical but often used in similar applications. |
| China | GB/T 4171 | Q415NH / Q500NH | Within the same standard: Q415NH offers lower strength, Q500NH offers higher strength, both with similar weathering characteristics. |
Notes:
Q460NH may be supplied with enhanced notch toughness (e.g., KV at -20°C) upon agreement. Pre-heating before welding is recommended for heavy sections. For severely corrosive environments or permanent immersion, a protective coating is still required. Always refer to the latest revision of GB/T 4171 for exact limits.
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