GB/T 4171 Q355GNH Atmospheric Corrosion-Resistant H-Beam

Q355NH H-Beam Steel is a weathering steel, belonging to the low-alloy high-strength structural steel category, and conforms to the GB/T 1591-2018 standard.

Q355NH steel has exceptional atmospheric corrosion resistance, making it particularly suitable for steel structures that are exposed to the atmosphere for extended periods.

It can maintain stable performance and structural strength even in harsh environments. While offering high strength, good toughness, and excellent weldability, this steel also provides outstanding weathering properties.

High Strength
The yield strength of Q355NH H-beam steel is no less than 355 MPa, and its tensile strength ranges from 470 to 630 MPa. The high strength allows it to meet the requirements of various complex structures, especially in high-load and extreme climatic conditions, where it can still maintain good bearing capacity.

Compared to ordinary steel, Q355NH has higher strength and better deformation resistance, ensuring that it does not easily undergo plastic deformation or failure under heavy loads.

Weather Resistance
Q355NH steel contains elements such as copper, nickel, phosphorus, and chromium, which significantly improve its corrosion resistance, particularly against atmospheric exposure, acid and alkali corrosion, humidity, and marine climates.

Copper enhances the steel's corrosion resistance in moist environments.

Nickel improves the steel's resistance to atmospheric oxidation.

Chromium and phosphorus help form a protective surface layer, enhancing the steel's weather resistance.

These characteristics make Q355NH particularly suitable for use in marine environments, chemical factories, outdoor buildings, and transportation infrastructure, where corrosion is more prevalent.

For example, Q355NH is ideal for structures like offshore platforms, bridges, tunnels, and chemical plants, which are exposed to natural elements for long periods. Using Q355NH can effectively reduce maintenance costs and extend service life.

Excellent Weldability
Q355NH H-beam steel has a low carbon equivalent, which makes it less likely to crack during welding, greatly improving welding quality.

The welded joints have stable performance, ensuring that the structure remains intact even under high stress and complex environmental conditions.

This feature makes Q355NH steel widely used in areas that require high-quality welding, such as bridge construction, heavy machinery, and steel structures.

Good Plasticity and Toughness
Q355NH maintains good plasticity and toughness both at room temperature and in low-temperature environments, providing strong impact resistance.

It is suitable for structures operating in both high and low-temperature conditions. The steel can effectively resist stress concentration caused by temperature variations and dynamic loads, preventing brittle fracture, especially in projects that need to maintain strength and durability under extreme conditions, such as steel structures in cold regions, cold chain logistics, and offshore engineering.

Fatigue Resistance
Q355NH H-beam steel has excellent fatigue resistance, meaning that it is less likely to develop fatigue cracks or damage under prolonged dynamic loads.

This makes it particularly suitable for projects like bridges, high-speed rail, heavy machinery, and transportation vehicles, which experience repetitive dynamic loads.

The strong fatigue resistance of Q355NH helps to extend the life of structures, reducing the frequency of maintenance and replacements.

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