What is the Difference Between Corten B and S355J2+N?

When selecting structural steel for outdoor or heavy-duty applications, understanding the difference between Corten B and S355J2+N is critical for cost, durability, and long-term performance.

At GNEE Steel, we are a professional steel manufacturer and global exporter with over 18 years of experience supplying weathering steel and structural steel to infrastructure, construction, and industrial projects worldwide. This guide explains Corten B vs S355J2+N in detail to help you make the right procurement decision.

Corten B, also known as weathering steel, is specially designed to form a stable rust-like protective layer when exposed to atmospheric conditions. This layer prevents further corrosion, eliminating the need for painting in many environments.

Key Characteristics of Corten B Steel

Corten B offers excellent atmospheric corrosion resistance, especially in outdoor structures such as bridges, containers, and facades. It is widely used in environments where maintenance costs must be minimized over time.

The chemical composition of Corten B includes copper, chromium, and nickel, which enhance its corrosion resistance properties. Compared with conventional carbon steel, it performs significantly better in harsh weather conditions.

Typical Applications of Corten B

Corten B is commonly used in:

• Bridge construction
• Railway wagons
• Shipping containers
• Architectural facades

Weathering steel facade 

S355J2+N is a normalized structural steel grade under EN 10025-2 standard. It is known for its high strength, good weldability, and excellent impact resistance at low temperatures.

Key Properties of S355J2+N Steel

The "+N" indicates normalized rolling or normalizing treatment, which improves toughness and consistency. The "J2" means it can withstand impact testing at -20°C, making it suitable for demanding structural applications.

Unlike Corten B, S355J2+N does not have inherent corrosion resistance and typically requires painting or galvanizing for outdoor use.

Typical Applications of S355J2+N

S355J2+N is widely used in:

• Steel structures and buildings
• Offshore platforms
• Machinery manufacturing
• Heavy equipment frames

Structural steel beams in factory workshop

Choosing between Corten B and S355J2+N depends on application environment, mechanical requirements, and lifecycle cost.

Corten B vs S355J2+N: Performance Comparison

Core Difference Summary

The most significant difference lies in corrosion resistance. Corten B naturally protects itself, while S355J2+N requires external coatings. However, S355J2+N offers better toughness and is more suitable for heavy-load structural applications.

Chemical composition plays a critical role in determining corrosion resistance, strength, and weldability. The addition of alloying elements such as Cu, Cr, and Ni is the key reason why Corten B exhibits superior weathering performance compared to S355J2+N.

Corten B vs S355J2+N: Chemical Composition Comparison Table

Selecting the right steel grade depends on your project's environment and performance requirements.

When Should You Choose Corten B?

Choose Corten B when:

• The structure is exposed to outdoor atmospheric conditions
• Maintenance cost reduction is a priority
• Aesthetic rust appearance is desired

Corten B is ideal for architectural and infrastructure projects where long-term durability and visual appeal are both important.

 Outdoor steel bridge made of weathering steel

When Should You Choose S355J2+N?

Choose S355J2+N when:

• High strength and toughness are critical
• The structure operates in low-temperature environments
• Protective coatings are acceptable

S355J2+N is more suitable for engineering structures that require strict mechanical performance.

At GNEE Steel, we combine manufacturing expertise with global supply capabilities to deliver high-quality Corten B and S355J2+N steel products.

Our Advantages

Full range of weathering and structural steel grades

• Strict quality control and international standards compliance
• Custom cutting, processing, and OEM services
• Fast delivery and professional export packaging
• Rich experience serving global EPC contractors and distributors

Steel plates packaging and shipment in warehouse

We understand the needs of overseas buyers and provide tailored solutions to reduce procurement risk and improve project efficiency.

In summary, the difference between Corten B and S355J2+N mainly lies in corrosion resistance, toughness, and application scenarios. Corten B is the best choice for outdoor, low-maintenance environments, while S355J2+N is ideal for high-strength structural applications requiring excellent mechanical performance.

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If you are looking for a reliable supplier of Corten B and S355J2+N steel, GNEE Steel is ready to support your project with competitive pricing, fast delivery, and professional service. Contact us today to get a free quote and technical consultation!

What is corten B?

Corten B is a weather resistant steel which is better suited for heavy and load bearing structures. The material forms its own protective layer when exposed to atmospheric elements. Essentially, the top layer corrodes which then protects the steel beneath it.

What is the difference between corten A and corten B?

CorTen A is often used for aesthetic purposes It is not recommended for use where the structure is subject to vibration. CorTen B is more suitable for load-bearing structures than it is more resistant to vibration or earthquake, and is often chosen due to its aesthetics and more uniform stains.

What is the US equivalent of S355J2 N?

ASTM A572 Grade 50 (USA):Widely used in construction and structural applications.

What is the meaning of S355J2 +N?

normalized structural steel grade

The S355J2+N is a normalized structural steel grade. An S355J2+N Plate has a chemical composition of carbon, manganese, silicon, phosphorous, carbon equivalent, sulfur, and copper content. The S355j2+n Chemical Composition gives its superior corrosion resistance properties in harsh environments.

What is the difference between S355J2 N and S355J2 AR?

S355J2 +AR steel plate and S355J2+ N steel plate differ primarily by the delivery condition when supplying, with S355J2+AR steel plate being delivered As Rolled, and S355J2+N steel plate being delivered after normalizing heating treatment.

Relying on many first-class equipment, such as CNC Shearing machine, Press Brake machine, Straightening machine, Roll Bending machine, Flat Bar Machine, Deburring machine etc, GNEE STEEL could provide various semi-productsand extensive forming services to customers.

GNEE STEEL  PROCESSING

CTL&SL

Grinding Polishing

Cutting

Beveling

Forming

Maching

Auto Welding

Heat treatment

Painting

Engineering Services

1.CTL & SL SERVICE (141 SETS)

Currently, GNEE STEEL has imported manyadvanced CTL/SL equipment from Italy and Korea and could provide customized CTL/SL services from cold rolled stainless steel and carbon steel to hot rolled stainless steel and carbon steel as well as strips and ultra-wide sheet.

CTL FACILITIES
Max Length:16500mm

Max Width:2200mm

Max Thickness:25.4mm

Max Yield Strength:1500Mpa
SL FACILITIES

Max Width:2200mm

Max Thickness:18mm

Max slit Quantity:31

Max Yield Strength:1200Mpa

2.CUTTING SERVICE

GNEE STEEL imported lots of advanced cutting machines from Germany, Sweden, America and Japan, including plasmas cutting machine, water jet cutting machine, laser cutting machine, flame cutting machine and saw machine. In order to meet customers' diversified needs, GNEE STEEL also adopts nest working multi-cutting methods and intensive production to improve production capacity and save costs for the customers.

Laser Cutting Machine

Max Cutting Length:40,000mm

Max Width:4,600mm
Max Thickness:100mm

Flame Cutting Machine

Max Cutting Length:40,000mm

Max Width:8,000mm
Max Thickness:500mm

Plasmas Cutting Machine

Max Cutting Length:30,000mm

Max Width:5,000mm
Max Thickness:100mm

Water-jet Cutting

Max Cutting Length:12,000mm

Max Width:4,010mm
Max Thickness:250mm

3.FORMING SERVICE

Steel Plate Roll Bending
Maximum Rolling Thickness: up to 200mm
Maximum Width: 4200mm

Automatic Bending Machine-Press Brake
Max Bending Capability:3000Ton
Max Bending Length:15,000mm

Expert in Bending High-Strength & Wear-Resistant Steels

Punching Machine

Max Width:3,070mm
Max Thickness:8mm

Max Pressure:250t

BEVELING SERVICE

GNEE STEEL beveling platform has edge milling machine, edge planer, flame / plasma groove cutting machine, flame groove cutting robot, desktop chamfering machine, gantry planerand other advanced equipment to provide customers with parts prefabrication services,daily processing of V-type, Y-type, X-type and U-type grooves, and guarantee subsequent processes such as welding and assembly of products.

Milling：
Max Cutting Length:18,000mm

Max Width:4500mm
Max Thickness:120mm

Beveling:
Max Length:16,000mm

Max Thickness:80mm

MACHINING SERVICE

GNEE STEEL owns CNC Portal-type Boring and Milling machine,CNC Floor-type Boring and Milling machine, Vertical Precision 5-axis Milling Machine, Portal-type Planer, Vertical Lathe, Cylindical Grinding machine, Hydraulic Planer and CNC Lathe and could provide fine machining of large spare parts and structural parts for customers.

Gantry Type Boring & Milling Maching Center

Max Length:48000mm

Max Width:12500mm
Max Height:8000mm

Max Diameter:10500mm

Deep-hole Drilling Equipment
Max Driling Depth:1,100mm
Max Bore Diameter:φ80mm
Max Diametar:φ4,500mm

MMulti-hole Drilling Equipment

Max Length:13,000mm
Max Width:10,000mm
Max Bore Diameter:φ105mm
Max Drilling Depth:250mm

Floor Boring And Milling Machine
Max Length:24,000mm
Max Height:8,000mm
Turntable Dimensions:9x5m

Vertical Lathe

Max Height:6,000mm

Max Diametar:φ22,00mm

Automated Edge Milling Machine

The Automated Edge Milling Machine is a leading product in heavy-duty milling equipment. It is primarily used for weld groove preparation (beveling) on large-format plates made of stainless steel, carbon steel, and special steel grades. It can process plates with a maximum thickness of up to 90mm, a length of 16 meters, and a width of 4 meters.

It is equipped with dual milling units and a fully automatic milling cutter head changing system, enabling automated 4-edge beveling. Its standout feature is the profiling technology used when milling wavy plates and irregularly shaped products, which ensures absolute consistency of the groove after milling.

Utilizing specially designed milling cutter heads, it can execute highly difficult and complex groove profiles in a single pass.

Materials: Plain carbon steel, pressure vessel steel, wear-resistant steel, high-strength steel, stainless steel, nickel-based alloys, etc.
Width: 1200 - 4200 mm
Length: 5800 - 16000 mm
Thickness: 5 - 90 mm
Weight: Up to 35 tons

This edge milling machine is the world's premier automated bevel milling equipment. With its excellent structural design and advanced data algorithms, it achieves full automation from plate detection to the actual milling process, significantly improving processing efficiency while guaranteeing high precision.

• Processing Accuracy

Length accuracy: ±1mm when L < 10m; ±2mm when L > 10m;

Width accuracy: ±1mm;

Diagonal accuracy: ±2mm;

Root face accuracy (blunt edge): ±1mm for Y-grooves; +0.5mm for X-grooves.

• Processing Efficiency

The processing efficiency is more than 10 times that of conventional edge milling or edge planing equipment.

HEAT TREATMENT

Heat Treatment Furnace
Max Furnace Size:36x12x13.5m
Max Rated Temperature:1100℃
Max Loading Capacity:800t

Heat Treatment of Pressure Vessels
Heat Treatment of Mining Equipment
Heat Treatment of Tube Sheet
Heat Treatment of Pressure Vessel Head

GNEE STEEL is currently participating in the procurement phase of a 100,000m³ full containment ammonia storage tank project, supplying high-quality steel plates for critical tank components. Due to the corrosive nature of ammonia and the risk of Ammonia Stress Corrosion Cracking (SCC), the project requires strict metallurgical control of materials according to EN 10028-3 standards.

One of the most important technical requirements of this project is the strict limitation of the actual Yield Strength (Re) for all NL2 grade materials. To prevent SCC risks in ammonia storage environments, the actual yield strength must not exceed 390 MPa, regardless of the nominal values specified in the standard or plate thickness ranges. This requirement places higher demands on steelmaking process control, heat treatment stability, and material testing.

Raw high-strength steel plates ready for the 100,000 m³ full containment ammonia storage tank production

Project Materials and Technical Requirements

The project mainly uses P355NL2 and P275NL2 normalized pressure vessel steel plates, which are widely applied in low-temperature storage tanks due to their excellent toughness and weldability.

Key technical specifications include:

• Material grades: P355NL2 and P275NL2 (Normalized)
• Yield strength: Standard minimum / Maximum limited to 390 MPa
• Hardness: ≤ 225 HBW in base material
• Impact testing: Charpy-V notch test at -50°C, minimum 27J
• Certification: EN 10204 3.1 certificate, with optional 3.2 certification

These strict requirements ensure that the steel plates maintain stable mechanical properties and high resistance to ammonia-induced stress corrosion during long-term operation.

Precision rolling and forming of steel plates into curved sections for the 100,000 m³ ammonia storage tank.

Project Plate Quantities and Thickness Distribution

The total steel demand for this ammonia storage tank project is several thousand tons, mainly distributed across different tank sections:

P355NL2 – Inner & Outer Tank Shell Plates

• Lower shell courses: 50 mm thickness – approx. 2,000 tons
• Middle shell courses: 25 mm thickness – approx. 1,400 tons
• Upper shell courses: 10 mm thickness – approx. 500 tons

P275NL2 – Tank Bottom Plates

• Thickness: 10–15 mm – approx. 750 tons

P275NL2 – Suspended Roof Structure

• Thickness: 5–8 mm – approx. 180 tons

S275JR – Outer Roof (Ambient Structure)

• Thickness: 10 mm – approx. 450 tons

To improve tank fabrication efficiency and reduce circumferential welds, the project also requires wide steel plates to minimize welding joints, which helps reduce the potential risk of SCC in ammonia service conditions.

Formed steel segments wrapped and racked for protection, ready for 100,000 m³ ammonia storage tank assembly.

GNEE STEEL provides high-precision steel plate rolling and cylinder fabrication solutions for tank manufacturers worldwide. Send us your plate specifications or fabrication drawings for a fast quotation.

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Stainless Steel Material and Surface Specifications

Special Steel / Nickel Base Alloy