Both Q345NQR4 and Q350EWR1 are atmospheric corrosion-resistant steels conforming to Chinese National Standards (GB), specifically designed for high-strength structural applications such as railway rolling stock, shipping containers, and bridges. When exposed to atmospheric environments, both steel grades form a self-protective rust layer, thereby reducing the need for painting; however, they differ in their specific strength parameters and primary application focuses.
What Is Q345NQR4 Atmospheric Corrosion-Resistant Steel Plates?
Q345NQR4 is an atmospheric corrosion-resistant steel-commonly referred to as weathering steel or Corten steel-specifically formulated to ensure exceptional performance even in harsh environments.
This steel grade belongs to the series of Chinese standard steels (typically classified under the TB/T 1979 standard) and is primarily utilized in the manufacture of railway rolling stock, shipping containers, and various other structural components that require superior resistance to atmospheric corrosion without the need for additional protective coatings.
Meaning of the Grade Designation:
Q: Represents the initial letter of the Chinese term for "Yield Strength."
345: Indicates a minimum yield strength of 345 MPa.
NQ: Signifies that this steel is specifically intended for railway vehicles (where "N" stands for railway, and "Q" stands for resistance to atmospheric corrosion).
R4: Refers to a specific chemical composition or performance grade within the standard for weathering steel.
What Is Q350EWR1 Atmospheric Corrosion-Resistant Steel Plates?
Q350EWR1 is a high-performance atmospheric corrosion-resistant steel (commonly referred to as weathering steel or Corten steel), specifically designed for harsh environments-particularly within the railway transportation industry.
It is characterized by its high strength, exceptional toughness, and the ability to form a dense, protective layer of rust on its surface; compared to ordinary carbon steel, this rust layer endows the material with a significantly superior service life.
Meaning of the Grade Designation
Q: Represents the initial letter of the Chinese Pinyin for "Yield Strength", used to indicate the steel's yield strength value.
350: Indicates that the minimum yield strength of this steel is 350 MPa.
E: Denotes the quality grade (impact toughness).
WR1: Indicates that this steel is a high-weather-resistant steel.
Q345NQR4 vs. Q350EWR1:Chmical Composition Compration
The fundamental difference between Q345NQR4 and Q350EWR1 lies in their alloying strategies and standard requirements: Q345NQR4 is designed primarily to withstand harsh atmospheric environments, typically featuring higher levels of copper (Cu), chromium (Cr), and nickel (Ni); whereas Q350EWR1 is classified as a standardized structural weathering steel (Grade E).
| Element | Q345NQR4 (Weathering) | Q350EWR1 (Weathering) |
|---|---|---|
| C | ≤ 0.16% | ≤ 0.12% |
| Si | 0.20% - 0.65% | ≤ 0.50% |
| Mn | 0.80% - 1.50% | 0.80% - 1.50% |
| P | ≤ 0.030% | ≤ 0.030% |
| S | ≤ 0.020% | ≤ 0.020% |
| Cu | 0.25% - 0.55% | 0.20% - 0.55% |
| Cr | 0.30% - 1.25% | 0.40% - 0.80% |
| Ni | 0.15% - 0.65% | ≤ 0.30% |
| Others | Micro-alloying (Nb, V, Ti) | Micro-alloying (Nb, V, Ti) |
Q345NQR4 vs. Q350EWR1:Mechanical Properties Compration
The mechanical properties of Q345NQR4 and Q350EWR1 are remarkably similar, as both are designed to provide high strength and durability in outdoor environments. However, Q350EWR1 holds a slight advantage in terms of yield strength and is often specifically engineered to demonstrate superior performance in heavy-duty welded structures.
| Property | Q345NQR4 | Q350EWR1 |
| Yield Strength |
≥345 |
≥350 |
| Tensile Strength | 490 – 630 | 480 – 630 |
| Elongation |
≥22 |
≥22 |
| Impact Test Temp | -20°C | -20°C (often up to -40°C) |
| Impact Energy |
≥34 |
≥34 |
Q345NQR4 vs. Q350EWR1:Main Applications Compration
Both Q345NQR4 and Q350EWR1 are high-strength atmospheric corrosion-resistant (weathering) steels; however, they are tailored to meet slightly different engineering requirements-particularly within China's railway and construction standards framework.
Q345NQR4 Main Applications
Heavy-Duty Coal Wagons (C70, C80): This represents the most widespread application area for this material.
Railway Open Wagons and Flatcars: Used for the transport of general cargo.
Standard Railway Containers: Mass-produced containers utilized for intermodal rail-road transport.
Regional Railway Bridges: Small-to-medium-scale structural components used in railway infrastructure construction.
Q350EWR1 Main Applications
High-Speed Rail (HSR) Components: Applied in the underframes and structural assemblies of advanced passenger coaches and Electric Multiple Units (EMUs).
Marine and Coastal Containers: Specialized containers designed specifically for use in high-salinity marine environments.
Long-Span Bridges: Utilized in large-scale bridge engineering projects.
Building Curtain Walls: Used for the exterior facade cladding of high-end architectural structures.
Environmental Protection Equipment: Applied in industrial facilities for equipment such as chimneys, dust collectors, and heat exchangers.
Q345NQR4 vs. Q350EWR1:Selection Guide
Select Q345NQR4 if the following conditions apply:
You are manufacturing standard railway freight vehicles.
The project involves traditional welding processes and requires proven impact performance at -20°C.
Initial material cost is a primary consideration in large-scale production.
Select Q350EWR1 if the following conditions apply:
You are designing advanced passenger trains or high-speed railway components.
The structural design involves complex automated welding processes, where the use of high-phosphorus steel (NQR4) poses a risk of cracking.
The structure is situated in a coastal or highly corrosive environment and requires "enhanced" corrosion resistance.
You require an additional 5 MPa increase in yield strength to optimize plate thickness and reduce overall weight.
If you require further details regarding our Q345NQR4/Q350EWR1 atmospheric corrosion-resistant steel plates, please do not hesitate to contact us.
As a leading manufacturer of Q345NQR4/Q350EWR1 atmospheric corrosion-resistant steel plates in China, GNEE boasts a deep industry legacy spanning 20 years. Our warehouses maintain a standing inventory of over 50,000 tons year-round, ensuring that orders can be dispatched in as little as 7 days. In terms of quality assurance, we are a dual-certified supplier-holding both API and ISO certifications-and we welcome inspections by third-party agencies such as SGS, BV, and Lloyd's.
By choosing our Q345NQR4/Q350EWR1 atmospheric corrosion-resistant steel plates, you will benefit from our comprehensive, customer-centric support services, as well as our extensive value-added processing capabilities. We would be delighted to provide full-scale support and assistance for your project.
Contact now to get Q345NQR4 atmospheric corrosion-resistant steel plates
| Product Name | Weather Resistant Steel Plate |
| Length | 4m-12m or as required |
| Width | 0.6m-3m or as required |
| Thickness | 0.1mm-300mm or as required |
| Standard | AISI,ASTM,DIN,JIS,GB,JIS,SUS,EN,etc. |
| Technique | Hot rolled |
| Surface Treatment | Clean, blasting and painting according to customer requirement |
| Thickness tolerance | ±0.1mm |
| Material | Q345NQR4,Q350EWR1 |
| Application | It is mainly used to make structural parts such as car girder, beam, transmission shaft and car chassis parts, which can reduce the weight of the parts. |
| MOQ | 1tons.We also can accept sample order. |
| Shipment time | Within 15-20 workdays after receiving deposit or L/C |
| Export packing | Waterproof paper, and steel strip packed. Standard Export Seaworthy Package.Suit for all kinds of transport,or as required |
| Capacity | 250,000 tons/year |
Can Q350EWR1 replace Q345NQR4?
Technically yes, it offers higher strength and better protection. It is a "performance upgrade" substitution, although the cost may be higher.
What alloying elements make Q350EWR1 superior?
It typically contains a more optimized balance of Copper (Cu), Chromium (Cr), Nickel (Ni), and sometimes Molybdenum (Mo) to enhance the protective layer.
Does Q350EWR1 require specialized storage?
No, like all weathering steel, it can be stored outdoors. However, keeping it dry and avoiding ponding water ensures a more uniform patina development later.
What is the main difference between Q345NQR4 and Q350EWR1?
Q345NQR4 is a standard railway weathering steel, while Q350EWR1 is an "Enhanced Weather Resistance" steel with slightly higher yield strength and superior corrosion resistance.