GB/T 4171 Q415NH is a weldable high-strength low-alloy weathering structural steel with excellent atmospheric corrosion resistance. By adding small amounts of alloying elements (Cu, Cr, Ni, etc.), it forms a natural protective film in outdoor environments while maintaining high strength, achieving a unique "rust-resistance mechanism" that provides 2–8 times greater atmospheric corrosion resistance than ordinary steel.

Q415NH steel requires minimal maintenance, significantly extends service life, and reduces maintenance costs. It is particularly suitable for engineering structures exposed to atmospheric environments over the long term. It perfectly balances mechanical performance, durability, economy, eco-friendliness, and aesthetic value, making it an ideal material choice for modern architecture, bridges, transportation facilities, and other exposed steel structures.

An appropriate quality grade (A/B/C/D/E) should be selected based on the engineering application environment (e.g., humidity, salt spray, temperature). 

Key Features and Advantages

1. Excellent Weather Resistance

The atmospheric corrosion resistance is 2-8 times that of ordinary carbon steel, significantly extending the service life in outdoor environments.

Without the need for painting or with simplified painting, it forms a dense, strongly adherent protective rust layer in natural settings, preventing further corrosion.

2. High Strength and Good Toughness

Yield strength ≥ 415 MPa, tensile strength ranging from 520 to 680 MPa, capable of bearing heavy loads, enabling thickness reduction, lowering material consumption, and reducing structural weight.

3. Good Weldability and Formability

It belongs to the category of weldable weathering steel, making it particularly suitable for engineering structures requiring welding.

It can be processed through welding, cold bending, stamping, and other methods under reasonable technical conditions.

4. Economic Efficiency

The price is significantly lower than that of stainless steel, offering high cost-effectiveness.

5. Maintenance-Free

After forming a stable rust layer on the surface, no painting or maintenance is required, significantly reducing long-term maintenance costs.

6. Unique Artistic Value

Its stable reddish-brown rust layer possesses a unique industrial aesthetic and historical gravitas, making it highly favored by architects.

Carbon Equivalent (CEV) of Q415NH Weathering Steel Plate (Corten Steel Plate) : ≤ 0.48%

* Calculate using the standard formula recommended by the International Institute of Welding (IIW): CE = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15

Note: "a" is the thickness of the steel material

Impact Energy

* The main difference lies in the varying impact test temperature requirements, ranging from Grade A (no requirement) to Grade E (-40°C), with progressively increasing demands for low-temperature toughness.

Q415NH Weathering Steel Plate (Corten Steel Plate) is widely used in structures that require long-term exposure to the outdoor atmosphere and pursue low maintenance costs or special aesthetic effects:

1. Architectural Field

Exterior structures of high-rise buildings, building curtain walls, exterior wall decoration, landscape architecture (such as park pavilions, landscape walls, viewing platforms), industrial plants, warehouses, etc.

2. Transportation Engineering

Bridge structures (especially in coastal and humid areas), trusses, box girders, highway guardrails, railway vehicles, freight carriages, containers, etc.

3. Industrial and Infrastructure

Transmission towers, wind turbine towers, PV power station supports, port facilities, marine engineering, communication towers, petrochemical equipment supports, etc.

4. Landscape Design

Urban sculptures, cultural landmarks (such as museum exteriors), art installations, landscape walls, planter boxes, seating, etc.

Precautions for Processing and Usage

1. Welding:

Use specialized welding materials compatible with weathering steel and follow appropriate welding procedures (e.g., controlling heat input, preheating, etc.) to maintain the corrosion resistance and mechanical properties of the weld zone.

2. Cutting:

Cutting is similar to that of ordinary steel, but attention must be paid to anti-corrosion treatment of the cut edges.

3. Initial Maintenance:

Before a stable rust layer forms (typically taking 1-3 years), surface issues such as rust runoff and uneven coloration may occur. "Stabilization treatment" (e.g., applying rust accelerators) can be employed to accelerate the formation of a uniform and aesthetically pleasing protective rust layer. Runoff rust water may stain surrounding walls or ground, so design considerations should include proper drainage and protection.

4. Coating:

Weathering steel can also be painted, as its weather resistance helps extend the coating's lifespan. Loose rust must be thoroughly removed before painting.

5. Environmental Limitations:

In environments with prolonged moisture, chlorine ions (e.g., marine or de-icing salt conditions), or severe industrial pollution, its corrosion resistance advantages may diminish. Careful evaluation or additional protective measures are required.

6. Design Specifications:

In structural design, its higher strength can be utilized to reduce the self-weight of the structure. However, attention must be paid to joint details to avoid water or dust accumulation.

Quality Grade Selection Guide

Comparison with Similar Steel Grades

Note: The same series of "GNH" grades (e.g., Q355GNH) are high weather resistance grades, offering better weather resistance but slightly poor weldability.