Description: BBN steel is a well-known steel manufacturer and service provider in China, GB/T 4171 Q355NH High strength weathering Steel Plate is our superior product, we are favored by customers with high quality, competitive price and excellent service
Payment Terms: L/C, T/T, D/P, Western Union, Paypal, Money Gram
Atmospheric Corrosion ResistanceGB/T 4171 Q355NH develops a dense, self-adhering protective rust layer on the surface in weather that resists atmospheric corrosion, superior to plain carbon steel.
355 MPa Class Min YieldQ355NH delivers thickness-dependent yield 355–325 MPa (by thickness) / 490–630 MPa tensile, enabling lighter-section designs.
Container-Grade WeatheringIdeal for unpainted shipping & offshore containers, weather shelters, tool boxes and workshop containers where maintenance cost is reduced.
01Product Overview & Specifications
GB/T 4171 Q355NH (also written as Q355NH) is a high-strength atmospheric corrosion resisting (weathering) 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 (thickness-dependent, 355 MPa at ≤16 mm down to 325 MPa for thickness >60 mm), Q355NH lets designers use lighter sections for cost reduction and is widely used in shipping containers, offshore containers and other outdoor 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 Strength)
Product Form
Weathering Steel Plate
Delivery Condition
Hot Rolledstandard delivery for GB/T 4171 plates; confirm per MTC
Thickness
2 – 300 mm
Width
1000 – 4200 mm
Length
3000 – 18000 mm
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, Q355NH is the high-strength base weathering grade; Q355GNH is the related higher-weathering-resistance 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)
Q355GNH (weathering steel within the same GB/T 4171 family, higher weathering resistance)
Designation basis
Q = yield strength; 355 = 355 MPa class min yield; NH = atmospheric corrosion resisting
Note: Q355NH and Q355GNH are both GB/T 4171 weathering steels. 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
GB/T 4171 Q355NH — how the designation breaks down.
Q
Q — Yield (Qu)
Q stands for the Chinese term for yield strength (屏服), the property class the grade is named by.
355
355 — 355 MPa Class
355 = 355 MPa-class minimum yield; at thickness ≤16 mm the minimum yield is 355 MPa, decreasing with thickness to 325 MPa for >60 mm.
NH
NH — Atmospheric Corrosion Resisting
NH = 胎候 (Nai Hou), i.e. atmospheric corrosion resisting; the steel forms a protective rust layer outdoors.
Q355NH processing note: Q355NH is a weathering steel; its alloying elements build the atmospheric-corrosion-resisting film. 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 GB/T 4171 Q355NH weathering steel (ladle analysis, %). "Max" denotes maximum allowed; ranges are min–max as per the provided analysis.
Element
Composition Range (%)
C (Carbon)
Max 0.16
Si (Silicon)
0.50
Mn (Manganese)
0.50 – 1.50
P (Phosphorus)
Max 0.030
S (Sulfur)
Max 0.030
Cu (Copper)
0.25 – 0.55
Ni (Nickel)
Max 0.65
Cr (Chromium)
0.40 – 0.80
05Mechanical Properties
Mechanical properties of GB/T 4171 Q355NH steel plate (per the provided thickness-based data). Yield strength decreases with thickness; tensile range applies to all thicknesses.
355 – 325 MPaYield Strength (by thickness)355 MPa ≤16 mm → 325 MPa >60 mm
490 – 630 MPaTensile StrengthMinimum – maximum
≥22%Min. Elongation A50GB/T 4171 Q355NH class min
GB/T 4171 Q355NH yield strength by thickness:
Thickness (mm)
Yield Strength (MPa, ≥)
Tensile Strength (MPa)
≤ 16
355
490 – 630
> 16 ≤ 40
345
> 40 ≤ 60
335
> 60
325
Note: Values above are the provided GB/T 4171 Q355NH requirements. Yield strength is thickness-dependent (higher for thinner plates). Elongation A50 ≥22% is the standard class minimum for the 355 MPa weathering grade; confirm full certification and impact testing in the MTC for your required condition.
06Product Types, Processing & Service
BBN Steel supplies GB/T 4171 Q355NH weathering steel plates with hot-rolled delivery condition, in thickness 2–300 mm, width 1000–4200 mm and length 3000–18000 mm. Plates are fully traceable with official Mill Test Certificates — ideal for unpainted outdoor and container structures.
1
Shipping & Offshore Containers
Q355NH is widely used for shipping containers and offshore containers, such as schedule waste storage containers and weather shelters, where the weathering layer cuts maintenance.
2
Shelters & Tool Boxes
Weather shelters, tool boxes and workshop containers benefit from Q355NH's atmospheric-corrosion resistance without repainting.
3
Cutting & Processing
Custom cutting, flattening and processing; third-party inspection supported for container and structural builds.
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
Thickness 2–300 mm, width 1000–4200 mm, length 3000–18000 mm
For shipping containers, offshore containers, weather shelters, tool boxes and workshop containers
Hot-rolled delivery; Mill Test Certificate (MTC) available; third-party inspection supported
Get Your GB/T 4171 Q355NH Quotation Now
Send us your dimensions (thickness × width × length), quantity, and application (e.g. shipping / offshore container, shelter or tool box). We will reply with stock status, competitive factory price and complete certification.
BBN Steel has established a complete set of production and supplier management system processes to ensure the improvement of product quality and better service to users.
Production Control
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