What is the difference between S355JR and S275JR?

When procuring non-alloy structural steels under the EN 10025-2 specification, engineers and purchasing managers are frequently tasked with choosing between S275JR and S355JR. Both grades are widely utilized in general construction, engineering, and infrastructure projects.

However, they differ significantly in load-bearing capacity, chemical composition, and fabrication requirements. As a leading manufacturer and exporter of high-quality structural steel plates, GNEE Steel has compiled this comprehensive guide to help you decide which grade best suits your project blueprint.

Decoding the Steel Designations: What Does "JR" Mean?

Before comparing their performance, it is essential to understand the European naming convention (EN 10025-2):

• "S" stands for Structural Steel.

• "275" or "355" denotes the minimum yield strength in Megapascals (MPa) for plates with a thickness of 16mm or less.

• "JR" is the impact testing suffix. It indicates that the steel has been Charpy V-Notch impact tested at room temperature (+20°C), achieving a minimum impact energy of 27 Joules.

(Note: Other common suffixes include J0 for 0°C testing, and J2 for -20°C testing. These grades are typically supplied in as-rolled or normalized conditions).

The Mill Test Certificate above is from a shipment of 30mm thick S355JR+AR steel plates, demonstrating our commitment to uncompromising metallurgical quality. 

S355JR vs S275JR: Mechanical Properties & Strength Gap

The primary difference between S275JR and S355JR is their mechanical strength. S355JR provides a significantly higher yield and tensile strength, allowing structural engineers to support greater loads using thinner steel sections (a cost-saving strategy known as "downgauging").

Chemical Composition and Welding Requirements

Both S275JR and S355JR offer excellent weldability, but the higher strength of S355JR requires a slightly altered chemical makeup, which affects fabrication procedures.

• Chemical Differences: To achieve 355 MPa, S355JR allows for higher Carbon (max 0.24% vs. 0.21%), Silicon (max 0.55% vs. 0.40%), and Manganese (max 1.60% vs. 1.50%) content compared to S275JR.

• Welding Precautions (CEV): Because of the increased alloying elements, S355JR has a higher Carbon Equivalent Value (CEV ≤ 0.45) than S275JR (CEV ≤ 0.40). While S275JR can be welded easily in almost all conditions, welding thick S355JR plates (> 40 mm) may require preheating (50–100°C) according to EN 1011-2 guidelines to prevent cold cracking in the Heat-Affected Zone (HAZ).

Application Guide: When to Choose Which Grade?

When should I choose S275JR over S355JR?

Use S275JR for cost-sensitive projects with moderate load requirements. Since a 275 MPa yield is entirely sufficient for light applications, it is the most economical choice for standard building frameworks, light bridges, pedestrian walkways, and general machinery base plates.

When is S355JR preferred over S275JR?

Choose S355JR for heavy-duty applications where structural integrity under extreme stress is non-negotiable. It is ideal for heavy bridges, offshore platforms, high-rise industrial structures, and crane components. Its superior strength allows designers to reduce material thickness and overall project dead-weight.

What is the main strength difference between S275 and S355?

S355 has a higher minimum yield strength (355 MPa vs. 275 MPa for ≤16 mm) and tensile strength (470–630 MPa vs. 410–560 MPa), enabling it to support greater loads with thinner sections.

Do S275 and S355 have similar impact properties?

Yes, for matching suffixes (JR: +20°C, J0: 0°C, J2: -20°C), both provide 27 J longitudinal impact energy. S355NL/S275NL are needed for -50°C.

How do their chemical compositions differ?

S355 allows higher carbon (0.24% vs. 0.21%), silicon (0.55% vs. 0.40%), and manganese (1.60% vs. 1.50%) for increased strength, with a higher CEV (0.45 vs. 0.40).

When should I choose S275 over S355?

Use S275 for cost-sensitive projects with moderate loads, like light buildings or standard frameworks, where 275 MPa yield is sufficient.

When is S355 preferred over S275?

Choose S355 for high-strength applications like heavy bridges, industrial structures, or cranes, where 355 MPa yield reduces material thickness.

Are welding requirements different for S275 and S355?

Both are weldable, but S355's higher CEV (≤0.45) may require preheating (50–100°C) for >40 mm thicknesses, unlike S275 (≤0.40). Follow EN 1011-2.

Extreme Cold Applications? Upgrade to Normalized Steel

S275JR and S355JR are excellent for general environments (+20°C). However, they do not possess mandatory fine-grain structures or -50°C low-temperature toughness. If your project is located in freezing climates (e.g., offshore Arctic rigs or winter construction), you must upgrade to EN 10025-3 specifications.

For a comprehensive overview of our en 10025 3 normalized steel plate offerings, including related low-temperature fracture-resistant grades like en 10025 3 s275nl normalized structural steel plate and en 10025 3 s355nl normalized structural steel plate, explore our full range. For extreme high-strength demands in freezing conditions, consider our en 10025 3 s420nl normalized structural steel plate.

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