What does G3 mean in S355J2G3?

Gangsteel, a leading manufacturer and exporter of structural steel plates, supplies premium EN 10025-2 S355J2 steel plates and equivalents for construction, bridges, and heavy machinery applications. S355J2G3 is an older designation for a non-alloy structural steel grade from the EN 10025 standard, widely used for its high strength, toughness, and weldability. The "G3" in S355J2G3 specifically refers to the delivery condition of the steel, indicating it is supplied in a "normalized" state. This article provides a detailed explanation of what G3 means in S355J2G3, including the breakdown of the grade designation, chemical composition, mechanical properties, applications, and comparisons with modern equivalents, helping engineers and fabricators understand its significance for material selection.

Breakdown of the S355J2G3 Grade Designation

The grade S355J2G3 is part of the old EN 10025:1990 + A1:1993 standard for hot-rolled structural steels, which has been superseded by EN 10025-2:2004. Each part of the designation has a specific meaning:

• S: Stands for "Structural steel," indicating the steel is intended for structural purposes rather than tool or high-speed steels.
• 355: Represents the minimum yield strength in MPa for plates up to 16 mm thick. For thicker plates, the yield strength decreases slightly (e.g., 345 MPa for 16–40 mm).
• J2: Specifies the impact toughness, requiring a minimum Charpy V-notch impact energy of 27 J at -20°C. This ensures the steel resists brittle fracture in cold conditions.
• G3: This is the key suffix denoting the "delivery condition." In the old EN 10025 standard, G3 indicates that the steel is supplied in a "normalized" condition, which involves heat treatment to refine the grain structure for improved toughness and uniformity.

In the updated EN 10025-2 standard, S355J2G3 is equivalent to S355J2+N, where "+N" explicitly means "normalized" or "normalized rolled." Normalization involves heating the steel to 870–900°C (above the austenite transformation temperature) and cooling it in air, which homogenizes the microstructure, reduces residual stresses, and enhances mechanical properties like ductility and impact resistance. This makes S355J2G3 particularly suitable for welded structures in demanding environments. For similar grades, explore Gangsteel’s EN 10025-2 S355J0 or EN 10025-2 S235J0.

Chemical Composition of S355J2G3

The chemical composition of S355J2G3 is optimized for strength, toughness, and weldability, with low carbon content to prevent brittleness. The table below shows the typical composition (% by weight) as per the old EN 10025 standard:

Key Notes:

• Carbon (C): Limited to 0.20% to ensure good weldability and ductility, preventing hardness in the heat-affected zone during welding.
• Manganese (Mn): Up to 1.60% enhances strength and toughness, crucial for load-bearing applications.
• Phosphorus (P) and Sulfur (S): Both capped at 0.035% to improve impact resistance and reduce brittleness, especially important for the J2 toughness designation.
• Nitrogen (N): Controlled at 0.009% max to promote fine grain structure, aiding the normalized (G3) condition.

This composition ensures S355J2G3 is a low-alloy steel with excellent formability. Gangsteel’s plates are produced with precise chemical control, often exceeding standard requirements for enhanced performance. For lower grades, check EN 10025-2 S275JR or EN 10025-2 S275J0 steel.

Mechanical Properties of S355J2G3

S355J2G3 exhibits robust mechanical properties, suitable for structural engineering. The table below summarizes its key properties for plates up to 16 mm thick, as per the old EN 10025 standard (values may vary with thickness):

Key Notes:

• Yield Strength: 355 MPa min allows for high-load applications, with values decreasing for thicker plates (e.g., 345 MPa for 16–40 mm).
• Tensile Strength: 490–630 MPa provides excellent resistance to breaking under tension.
• Elongation: 22% ensures good ductility for forming and welding.
• Impact Toughness: 27 J at -20°C guarantees resistance to brittle failure in cold conditions, a key feature for outdoor structures.
• Hardness: 150–200 HB indicates moderate hardness, easy to machine while durable.

The normalized (G3) condition refines the grain structure, improving these properties compared to as-rolled steels. For higher toughness, consider EN 10025-2 S355K2 steel or EN 10025-2 S450J0 steel from Gangsteel.

Weldability and Fabrication of S355J2G3

S355J2G3 has excellent weldability due to its low carbon equivalent (CEV max 0.45 for thicknesses up to 30 mm), allowing for welding without preheating in many cases. It is compatible with common welding methods like SMAW (using low-hydrogen electrodes such as E7018), GTAW, and SAW. For thicker plates (>40 mm), preheating to 100–150°C is recommended to avoid cracking in the heat-affected zone (HAZ).

Fabrication properties include good machinability and formability, with the normalized (G3) condition reducing distortion during heat treatment. Post-weld heat treatment (PWHT) at 600–650°C is advised for stress relief in ASME-coded applications. Gangsteel’s S355J2G3 plates are supplied with optimized bonding for reliable welding, similar to EN 10025-2 S235J2 steel but with higher strength.

Applications of S355J2G3 Steel Plates

S355J2G3 is versatile and widely used in applications requiring high strength and toughness:

1. Construction: For high-rise buildings, bridges, and stadiums, where its yield strength and low-temperature toughness are essential.
2. Offshore Engineering: In platforms and wind turbines, leveraging its corrosion resistance and impact toughness.
3. Heavy Machinery: For cranes, excavators, and mining equipment, where durability under dynamic loads is critical.
4. Shipbuilding: In hulls and superstructures, benefiting from its weldability and strength.
5. Energy Sector: For pipelines and storage tanks, offering reliability in varying temperatures.

Gangsteel’s S355J2G3 plates are available in thicknesses from 6–300 mm, with options for cut-to-size and cladding for specialized applications like EN 10025-2 S355JR+N.

Comparison with Modern EN 10025-2 Grades

S355J2G3 from the old EN 10025 is equivalent to S355J2+N in the current EN 10025-2:2004 standard, where "+N" explicitly denotes normalized delivery. The table below compares S355J2G3 with other EN 10025-2 grades:

S355J2G3's mandatory normalized condition (G3) provides better uniformity than as-rolled grades like S355JR, making it preferable for legacy projects. Gangsteel offers modern equivalents like EN 10025-2 S355J2 steel.

Why Choose Gangsteel for S355J2G3 Steel Plates?

Gangsteel is a trusted supplier of S355J2G3 and equivalent plates, offering:

• Certified Quality: Plates undergo ultrasonic testing, Charpy impact tests at -20°C, and chemical analysis to meet EN 10025 standards.
• Customization: Available in thicknesses from 6–300 mm, with options for normalization (G3 condition), cut-to-size, and beveling.
• Global Supply: Competitive pricing and reliable delivery from China to worldwide markets.
• Technical Support: Guidance on selecting S355J2G3 versus modern grades like EN 10025-2 S355JR steel or EN 10025-2 S355K2 steel.
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Gangsteel Solution

S355J2G3 is a structural steel grade where "G3" indicates normalized delivery condition, improving toughness and uniformity. Gangsteel’s high-quality S355J2G3 plates ensure reliability for your projects. For equivalent standards, explore our BS EN 10025-2 material grade guide.

Gangsteel

Gangsteel explains what G3 means in S355J2G3, detailing the grade designation, chemical composition, mechanical properties, and applications.

Keywords: S355J2G3 delivery condition, EN 10025 S355J2G3, S355J2G3 normalized steel, S355J2G3 properties