Introduction

S355J2G3 is a non-alloy structural steel grade that offers a combination of excellent strength, good toughness, and outstanding weldability. Classified under the European EN 10025 standard, it is one of the most popular structural grades used across multiple industries. With its low carbon content and fine-grain structure, S355J2G3 ensures high reliability in demanding environments, including low-temperature service conditions.

Properties of S355J2G3 Grade:

  • High tensile and yield strength
  • Excellent toughness, even at low temperatures (Charpy impact tested at -20°C)
  • Very good weldability without the need for preheating
  • Good machinability
  • Fine-grained structural steel for superior mechanical performance
  • Suitable for applications requiring better notch toughness

Uses/Applications of S355J2G3 Grade:

  • Construction of bridges, buildings, and offshore structures
  • Manufacturing of heavy machinery
  • Fabrication of cranes, frames, and industrial equipment
  • Truck frames, trailer components, and chassis
  • Wind towers and energy sector structures
  • Railway vehicles
  • Pressure vessels and pipelines (non-critical services)
  • Structural components subjected to dynamic loading

Chemical Composition (Typical):

Element Content (%)
Carbon (C) ≤ 0.20
Manganese (Mn) 1.00 – 1.60
Silicon (Si) ≤ 0.55
Phosphorus (P) ≤ 0.035
Sulfur (S) ≤ 0.035
Nitrogen (N) ≤ 0.012
Iron (Fe) Balance

Mechanical Properties (Typical):

Property Value
Tensile Strength 470 – 630 MPa
Yield Strength (minimum) 355 MPa (for thickness ≤ 16 mm)
Elongation (in 50 mm gauge length) 18% minimum
Charpy V-Notch Impact Test ≥ 27 Joules at -20°C
Brinell Hardness (approx.) 146 – 187 HB

Physical Properties:

Property Value
Density 7.85 g/cm³
Modulus of Elasticity 210 GPa
Poisson’s Ratio 0.3
Thermal Conductivity ~ 50 W/m·K
Specific Heat ~ 450 J/kg·K
Electrical Conductivity ~ 10% IACS

Forging:

Forging of S355J2G3 is generally performed between 1100°C and 850°C:

  • Start forging at 1100°C and finish at around 850°C.
  • Slow furnace cooling is recommended post-forging to prevent the formation of unwanted microstructures.

Heat Treatment:

S355J2G3 is usually supplied in a normalized or normalized rolled condition to refine grain structure and enhance mechanical properties.

  • Normalizing Temperature: 890°C – 940°C
  • Stress Relieving: Typically at 530°C – 580°C after heavy forming or welding.
  • No hardening by heat treatment without altering its structure — however, surface treatments like case hardening are possible if needed.

Dimensional Tolerances:

Manufactured as per EN 10025 standards:

  • Hot Rolled Bars: Standard tolerances, suitable for structural use.
  • Cold Finished Bars: Tighter tolerances available for precision applications.

Custom tolerances are available upon request depending on project specifications.

Machinability:

S355J2G3 offers good machinability:

  • Rated at about 60%-70% of free-machining steel grades.
  • Suitable for conventional machining processes: drilling, milling, turning, and tapping.
  • Carbide or high-speed steel tools recommended.
  • Proper lubrication and cooling can significantly improve tool life and surface finish.

Corrosion Resistance:

  • Moderate corrosion resistance in dry atmospheric conditions.
  • For outdoor applications or aggressive environments, protective coatings such as painting, hot-dip galvanizing, or powder coating are recommended.
  • Not inherently resistant to marine or chemically aggressive environments without surface protection.

Weldability:

S355J2G3 has excellent weldability:

  • No need for preheating in most cases due to its low carbon equivalent (CE).
  • Compatible with all standard arc welding processes (MIG/MAG, TIG, SMAW, SAW).
  • Post-weld stress relieving may be necessary for thick sections or critical applications.

Recommended practices:

  • Use low hydrogen electrodes.
  • Follow correct welding parameters to avoid cold cracking.

Available Form:

  • Hot Rolled Round Bars
  • Square Bars
  • Flat Bars
  • Hexagonal Bars
  • Cold Finished Bars (Bright Bars)
  • Forged Bars
  • Plates and Structural Sections (I-beams, channels, angles)
  • Coils and Sheets (upon request)

Conclusion:

S355J2G3 carbon steel bar is an exceptional choice for applications demanding a balance of high strength, good toughness, and excellent weldability. It performs reliably under dynamic loads and low-temperature service, making it a trusted material for construction, heavy machinery, transportation, and structural engineering projects. With the right protective measures, it offers long-lasting performance across various industrial environments.

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