Description: BBN steel is a well-known steel manufacturer and service provider in China, China GB/T 4171 Q355GNH Weather Resistant Steel Plate is our superior product, we are favored by customers with high quality, competitive price and excellent service
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China GB/T 4171 Q355GNH Weather Resistant Steel Plate | Atmospheric Corrosion Resisting Steel for Vehicle, Bridge, Tower & Container
Weathering / Atmospheric Corrosion Resisting Steel (GB/T 4171 Q355GNH) | Forms a Protective Rust Layer Outdoors | Vehicle, Bridge, Tower, Container & Building | MTC & Third-Party Inspection
Atmospheric Corrosion ResistanceGB/T 4171 Q355GNH develops a dense, self-adhering protective rust layer on the surface in weather that resists atmospheric corrosion, superior to plain carbon steel.
Min. Yield 355 MPa (Q355)Q355GNH delivers 345–355 MPa yield / 490–630 MPa tensile, enabling lighter-section designs and cost reduction.
Reduced MaintenanceIdeal for unpainted use where painting/maintenance cost is reduced; widely used in vehicles, bridges, towers and containers.
01Product Overview & Specifications
China GB/T 4171 Q355GNH (also written as Q355GNH) is a high-weathering-resistance atmospheric corrosion resisting steel under the Chinese national standard GB/T 4171. Its special chemistry builds a dense, protective rust layer on the metal surface that resists atmospheric corrosion, superior to regular carbon steel.
With a 355 MPa-class minimum yield (measured 345–355 MPa), Q355GNH lets designers use lighter sections for cost reduction, and is widely used in vehicles, bridges, towers, containers and building structures where a maintenance-free weathering surface is valued.
GB/T 4171 (Chinese national standard for weathering steel)
Steel Category
Weathering Steel (Atmospheric Corrosion Resisting / High Weathering Resistance)
Product Form
Weathering Steel Plate
Delivery Condition
Hot Rolledstandard delivery for GB/T 4171 plates; confirm per MTC
Thickness Range
All common thickness specsper GB/T 4171 & order
Width × Length
Per order specification
MOQ
1 PC
Delivery Time
Promptly (Stock) / Custom production: 10 – 40 working days
Stock Status
In stock & custom productionconfirm current stock on inquiry
Certification
Mill Test Certificate (MTC) available, third-party inspection supported
Payment Terms
T/T, L/C At Sight
02Standard & GB/T 4171 Grade Family (Q355NH vs Q355GNH)
GB/T 4171 is the Chinese national standard for weathering (atmospheric corrosion resisting) structural steel. Within it, Q355GNH is the high-weathering-resistance grade; Q355NH is the related base weathering grade. Both share the corrosion-resisting concept but differ in exact composition limits and certification — confirm against the ordered specification and Mill Test Certificate (MTC) before design-critical use.
Item
Grade / Note
Standard
GB/T 4171 (China national standard for weathering steel)
Q355NH (weathering steel within the same GB/T 4171 family)
Designation basis
Q = yield strength; 355 = 355 MPa class min yield; G = high (weathering resistance); NH = atmospheric corrosion resisting
Note: Q355GNH and Q355NH are both GB/T 4171 weathering steels. Q355GNH is the higher-weathering-resistance variant. For international cross-references or design-critical substitution, verify composition limits and certification under the target standard and against the Mill Test Certificate (MTC).
03Grade Designation & Meaning
China GB/T 4171 Q355GNH — how the designation breaks down.
Q
Q — Yield (Qu)
Q stands for the Chinese term for yield strength (屈服), the property class the grade is named by.
355
355 — 355 MPa Class
355 = 355 MPa-class minimum yield; the provided data shows a measured yield range of 345–355 MPa.
G
G — High Weathering
G denotes the higher-weathering-resistance variant of the GB/T 4171 family (vs the base Q355NH).
NH
NH — Atmospheric Corrosion Resisting
NH = 耐候 (Nai Hou), i.e. atmospheric corrosion resisting; the steel forms a protective rust layer outdoors.
Q355GNH processing note: Q355GNH is a weathering steel; its alloying elements build the atmospheric-corrosion-resisting film, so forming is somewhat more difficult than plain carbon steel. It can be moderately drawn and is easily welded with common procedures; delivery is typically hot rolled, and thickness/width/length are per customer order and confirmed in the Mill Test Certificate (MTC).
04Chemical Composition
Chemical composition of China GB/T 4171 Q355GNH weathering steel (ladle analysis, %). "Max" denotes maximum allowed; the provided analysis lists the five elements below.
Element
Composition Range (%)
C (Carbon)
Max 0.15
Si (Silicon)
0.25 – 0.75
Mn (Manganese)
Max 1.0
P (Phosphorus)
0.07 – 0.15
S (Sulfur)
Max 0.02
Note: The provided analysis lists C, Si, Mn, P and S. Other weather-resisting alloying elements (such as Cu, Cr, Ni) that strengthen the protective rust layer are specified by GB/T 4171 and stated in the Mill Test Certificate (MTC) for each heat/coil — verify the exact heat-analysis against your ordered specification.
05Mechanical Properties
Mechanical properties of China GB/T 4171 Q355GNH steel plate (per the provided data). Standard public values for the GB/T 4171 weathering-steel family.
345 – 355 MPaYield Strength355 MPa class
490 – 630 MPaTensile StrengthMinimum – maximum
22%Min. Elongation A50Minimum
China GB/T 4171 Q355GNH mechanical properties:
Grade
Yield Strength (MPa)
Tensile Strength (MPa)
Elongation A50 (%)
China GB/T 4171 Q355GNH
345 – 355
490 – 630
22 (min)
Note: Q355GNH is a weathering steel; the values above are the provided minimum/range requirements for GB/T 4171. Because it contains more alloying elements than plain carbon steel, forming is somewhat more difficult and it can be moderately drawn; it is easily welded with common procedures. Impact testing and full certification are confirmed in the MTC for your required condition.
06Product Types, Processing & Service
BBN Steel supplies China GB/T 4171 Q355GNH weathering steel plates with hot-rolled delivery condition. Plates are fully traceable with official Mill Test Certificates — ideal for unpainted outdoor and weathering structures.
1
Weathering Steel Plate
Hot-rolled Q355GNH plates in all common thicknesses, customizable fixed length per your drawings.
2
Stock & Custom
Common sizes shipped promptly from stock; custom production both available.
3
Cutting & Processing
Custom cutting, flattening and processing; third-party inspection supported.
1
Fast Delivery
Common sizes shipped promptly from stock; custom production 10–40 working days.
2
MTC & Inspection
Mill Test Certificates available; third-party quality inspection supported.
3
Flexible Payment
T/T and L/C at sight accepted for your convenience.
4
24h Consultation
Professional sales team provides 24-hour online consultation and quotation.
Forms a dense protective rust layer outdoors — superior atmospheric corrosion resistance vs carbon steel
For vehicles, bridges, towers, containers and building structures
Hot-rolled delivery; thickness, width and length per customer order and confirmed in MTC
Mill Test Certificate (MTC) available; third-party inspection supported
Get Your China GB/T 4171 Q355GNH Quotation Now
Send us your dimensions (thickness × width × length), quantity, and application (e.g. vehicle, bridge, tower or container). We will reply with stock status, competitive factory price and complete certification.
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