EN 10025-2 S355J2 is a European standard for hot-rolled structural steels, specifically a non-alloy structural steel with a minimum yield strength of 355 MPa and improved impact toughness at low temperatures.

Standard and Grade Designation

Standard: EN 10025-2

This is the European standard for "Hot rolled products of structural steels - Part 2: Technical delivery conditions for non-alloy structural steels."

Grade: S355JR

"S" = Structural steel

"355" = Minimum yield strength of 355 MPa (at ≤16mm thickness)

"J2" = Impact toughness requirement at -20°C (27J min, longitudinal Charpy V-notch test)

Material Type: Non-alloy steel (but may contain small amounts of alloying elements like Mn, Si, etc.)

Delivery Condition: Typically hot-rolled (as-rolled) or normalized

The characteristics of S355J2 High-Strength Low-Alloy Steel Plate are as follows: 

1. High strength and toughness, able to withstand large pressure and impact loads.

2. Good corrosion resistance, suitable for use in harsh environments.

3. Good welding properties, can be welded by various conventional welding methods.

4. good processing properties, easy to cut, bend and form.

Carbon Equivalent of S355J2 High-strength Low-alloy Steel Plate

* The carbon equivalent value varies depending on the thickness.For detailed information, please contact us for inquiries.

* Carbon equivalent (CEV) is calculated using the International Institute of Welding (IIW) formula:

CEV = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15

* The actual yield strength value decreases as the material thickness increases.

S355J2 is widely used due to its high strength, good toughness, and moderate cost in:

1. Building structures: Steel frames, beams, columns, etc.

2. Bridge engineering: Bridge components, support structures.

3. Mechanical manufacturing: Heavy machinery parts, equipment bases.

4. Pressure vessels: Low-pressure containers (non-high temperature/pressure, subject to additional relevant standards).

5. Vehicle manufacturing: Truck frames, construction machinery chassis, etc.

The delivery state of S355J2 Low-Alloy High-Strength Steel Plate:

The delivery condition of S355J2 Low-Alloy High-Strength Steel Plate generally includes hot-rolled, controlled-rolled, normalized or normalized plus tempered states. Among them, the surface of the steel plate in the hot-rolled state is rougher and requires subsequent processing, while the surface of the steel plate in the normalized or normalized plus tempered state is relatively smooth and can be directly used for manufacturing various steel structural parts. In addition, according to the customer's needs, processing treatments such as cutting, sawing, bending, punching and painting can also be carried out to meet different usage requirements.

Material Properties: Why Is S355J2 Widely Used?

The reason S355J2 is regarded as a "universal structural steel" lies in its well-balanced performance advantages:

Balance of Strength and Toughness: With a yield strength of 355 MPa, it significantly exceeds that of basic structural steel S235 (235 MPa). Additionally, its impact energy at 0°C is ≥34 J, ensuring both load-bearing capacity and impact resistance, making it suitable for multi-load scenarios.

Excellent Weldability: Its low carbon (≤0.24%), low sulfur, and low phosphorus composition reduce the risk of cracking during welding. Complex preheating or post-weld heat treatments are generally unnecessary (except for thick-plate welding), lowering construction costs.

Superior Processability: It can undergo conventional cold processing such as cutting, drilling, bending, and stamping, as well as hot processing (e.g., forging) to adjust its shape, meeting the requirements of various structural components.

Cost-Effectiveness: As a non-alloy steel, its production cost is lower than that of high-strength alloy steels (e.g., Q690), while its performance meets the demands of most structural applications, offering exceptional cost efficiency.

Precautions: Key Points to Consider During Use

Thickness Effect: When the steel plate thickness exceeds 40mm, mechanical properties may slightly decrease (e.g., yield strength may drop to 345MPa, elongation may reduce). Designers should refer to the "thickness segment requirements" in the standard.

Low-Temperature Application Limitations: The impact test temperature for S355J2 is -20°C. If used in low-temperature environments below -20°C (e.g., outdoor equipment in cold regions), grades with lower impact temperatures (such as S355K2 or S355NL) must be selected.

Welding Process Compatibility: Although it has good weldability, preheating (typically 80-150°C) is required before welding thick plates (>60mm) to avoid cold cracking. Welding wires/electrodes must be selected to match the strength grade (e.g., ER50 series welding wires).

Surface Treatment: If used outdoors or in corrosive environments, anti-corrosion treatments (such as hot-dip galvanizing or painting) are necessary to extend service life.

Comparison with Other S355 Grades:

Summary

EN10025-2 S355J2 is a well-balanced and widely used structural steel. Its core advantages lie in its "high strength + good low-temperature toughness + ease of processing," making it one of the preferred materials for structural components in projects across Europe and worldwide.