S355J2 is a European structural steel grade classified as a low-carbon mild steel under the EN 10025 standard. It is well known for its excellent weldability, high strength, and reliable toughness, making it a preferred material for a broad range of load-bearing and engineering applications.
The main alloying elements-carbon (C), manganese (Mn), and silicon (Si)-are carefully controlled to deliver a balanced combination of strength, ductility, and fabrication performance.
1. General Overview
S355J2 is designed for structural and engineering uses where mechanical strength and weldability are critical.
"S" indicates structural steel
"355" represents the minimum yield strength of 355 MPa (for thickness ≤ 16 mm)
"J2" confirms impact toughness tested at −20°C, ensuring suitability for cold-service environments
Key Characteristics
High load-bearing capacity: Minimum yield strength of 355 MPa
Excellent weldability: Compatible with standard welding techniques
Wide applicability: Commonly used in construction, automotive, and industrial manufacturing
1.1 Advantages and Limitations
| Advantages | Limitations |
|---|---|
| High strength-to-weight ratio | Limited corrosion resistance without surface protection |
| Very good weldability | Not recommended for prolonged high-temperature service |
| Good machinability | Risk of brittle fracture if improperly handled at low temperatures |
S355J2 has become a cornerstone material in modern construction, offering a cost-effective and dependable solution for structural frameworks, bridges, and industrial buildings.
2. Alternative Names, Standards & Equivalent Grades
| Standard | Grade | Region | Remarks |
|---|---|---|---|
| EN | S355J2 | Europe | Standard structural steel |
| ASTM | A572 Grade 50 | USA | Closest equivalent with slight chemistry differences |
| DIN | St52-3 | Germany | Comparable strength, different impact requirements |
| JIS | SM490A | Japan | Similar performance, different yield limits |
While these grades are often considered interchangeable, variations in chemistry and testing requirements may influence performance in specific applications.
3. Technical Properties
3.1 Chemical Composition
| Element | Typical Range (%) |
|---|---|
| Carbon (C) | 0.17 – 0.20 |
| Manganese (Mn) | 1.20 – 1.60 |
| Silicon (Si) | 0.10 – 0.50 |
| Phosphorus (P) | ≤ 0.035 |
| Sulfur (S) | ≤ 0.035 |
Element Functions:
Carbon: Improves strength and hardness
Manganese: Enhances tensile strength and hardenability
Silicon: Increases strength and oxidation resistance
3.2 Mechanical Properties
| Property | Test Condition | Typical Value |
|---|---|---|
| Yield Strength | Room temperature | ≥ 355 MPa |
| Tensile Strength | Room temperature | 470 – 630 MPa |
| Elongation | Room temperature | ~21% |
| Impact Energy | −20°C (Charpy V) | 27 J |
| Hardness | Brinell | 170 – 210 HB |
These properties allow S355J2 to withstand high structural loads while maintaining sufficient ductility and impact resistance, especially in cold climates.
3.3 Physical Properties
| Property | Value |
|---|---|
| Density | 7850 kg/m³ |
| Melting Point | 1420 – 1540 °C |
| Thermal Conductivity | ~50 W/m·K |
| Specific Heat Capacity | ~470 J/kg·K |
| Thermal Expansion | 12 × 10⁻⁶ /°C |
3.4 Corrosion Resistance
S355J2 offers moderate resistance to atmospheric corrosion, but it is not corrosion-resistant by design.
| Environment | Resistance Level | Recommendation |
|---|---|---|
| Atmospheric | Fair | Protective coating advised |
| Chloride exposure | Poor | Not recommended |
| Acidic media | Poor | Avoid use |
| Alkaline conditions | Fair | Surface protection suggested |
For aggressive environments, coating, painting, or galvanizing is strongly recommended.
4. Heat Resistance
| Condition | Temperature Limit | Notes |
|---|---|---|
| Continuous service | ≤ 400 °C | Acceptable for structural use |
| Intermittent service | ≤ 500 °C | Short exposure only |
| Scaling risk | ≥ 600 °C | Oxidation increases rapidly |
5. Fabrication Characteristics
5.1 Weldability
S355J2 demonstrates excellent welding performance using conventional methods:
| Welding Process | Typical Filler | Notes |
|---|---|---|
| MIG | ER70S-6 | Ideal for thin sections |
| TIG | ER70S-2 | High-quality precision welds |
| SMAW | E7018 | Common for heavy structures |
Preheating is recommended for thicker plates or low-temperature environments to minimize cracking risks.
5.2 Machinability
S355J2 offers good machinability, though cutting speeds should be lower than free-machining steels. Proper tooling and cooling improve tool life and surface finish.
5.3 Formability
The steel can be cold-formed and hot-formed with minimal cracking risk. Care should be taken during cold forming to avoid excessive strain hardening.
5.4 Heat Treatment
| Process | Temperature | Purpose |
|---|---|---|
| Normalizing | 900 – 950 °C | Grain refinement, improved toughness |
| Quenching | 850 – 900 °C | Increased hardness |
| Tempering | 500 – 700 °C | Reduced brittleness, better ductility |
Heat treatment can be applied to optimize mechanical performance depending on service requirements.
What material is S355J2?
S355J2 is a medium tensile, low carbon manganese steel which is readily weldable and possess good impact resistance (also in sub-zero temperatures). This material is commonly supplied in the untreated or normalized condition.
What is the equivalent material of S355J2?
The equivalent of S355J2 EN 10025-2 is ASTM A572 Grade 50, DIN ST52-3, JIS SM490YA, and GB Q355D, with similar high strength and low-temperature toughness for structural use. Gangsteel's high-quality plates ensure compliance for your projects. For more, explore our BS EN 10025-2 material grade guide.
What is the difference between S355JR and S355J2?
S355JR steel has a minimum impact strength of 27 J under 20-degree temperature conditions while the second type of steel, S355J2+N has the same impact strength but with a temperature of -20 degrees.
What is the ASTM equivalent of S355J2?
The ASTM equivalent of S355J2 is A572 Grade 50, with similar high strength and low-temperature toughness for structural use. Gangsteel's high-quality plates ensure compliance for your projects. For more, explore our BS EN 10025-2 material grade guide.
What is the yield strength of S355J2 steel?
Grade S355J2 has a minimum yield strength of 355 MPa.