1. Product Introduction
S355J2H is a high-quality non-alloy fine-grained structural steel hollow section delivered in the hot-finished condition. The "H" suffix specifically denotes that it is a Hollow Section.
This grade is one of the most common and widely used structural steels in Europe for load-bearing components in construction and mechanical engineering.
S355: Indicates the minimum yield strength of the steel at 16mm thickness is 355 MPa (N/mm²). This is the primary characteristic defining its load-bearing capacity.
J2: This designates the impact toughness (notch toughness) requirements. The "J2" means the steel is tested at -20°C and must achieve a minimum impact energy of 27 Joules (longitudinally). This makes it suitable for applications in cold climates or where dynamic loading is a concern.
H: Stands for Hollow Section (as per EN 10210). This distinguishes it from flat products (plate, sheet) or open sections (beams, channels).
Key Features:
High Strength-to-Weight Ratio: Offers excellent strength without excessive weight.
Good Weldability and Machinability: Due to its controlled chemical composition.
Good Toughness: The guaranteed impact energy at -20°C makes it reliable for demanding applications.
Standardized Dimensions: Produced to strict dimensional tolerances.
Main Standard: The governing standard for S355J2H hot-finished hollow sections is EN 10210-1:2006 and EN 10210-2:2006.
2. Chemical Composition (By Weight %)
The composition is strictly controlled to ensure the mechanical properties. Maximum values are as follows (ladle analysis):
| Element | Carbon (C) | Silicon (Si) | Manganese (Mn) | Phosphorus (P) | Sulfur (S) | Note |
|---|---|---|---|---|---|---|
| Max % | 0.22 | 0.55 | 1.60 | 0.035 | 0.035 | The Cu content is typically ≤ 0.55%. |
Note: The carbon equivalent (CEV) is calculated to ensure weldability. For S355J2H, the maximum CEV is typically 0.45% for sections with a thickness ≤ 40mm.
3. Mechanical Properties
These are the minimum guaranteed properties as per EN 10210-1.
Mechanical Properties Table
| Thickness (t) [mm] | Yield Strength (ReH) Min [MPa] | Tensile Strength (Rm) [MPa] | Elongation (A) Min [%] | Impact Energy (KV) Min [J] |
|---|---|---|---|---|
| t ≤ 16 | 355 | 470 - 630 | 22 | 27 J at -20°C |
| 16 < t ≤ 40 | 345 | 470 - 630 | 22 | 27 J at -20°C |
| 40 < t ≤ 63 | 335 | 470 - 630 | 22 | 27 J at -20°C |
| 63 < t ≤ 80 | 325 | 470 - 630 | 21 | 27 J at -20°C |
| 80 < t ≤ 100 | 315 | 470 - 630 | 20 | 27 J at -20°C |
| 100 < t ≤ 120 | 305 | 450 - 610 | 19 | 27 J at -20°C |
| 120 < t ≤ 150 | 295 | 450 - 610 | 18 | 27 J at -20°C |
| 150 < t ≤ 200 | 285 | 450 - 610 | 17 | 27 J at -20°C |
| 200 < t ≤ 250 | 275 | 450 - 610 | 16 | 27 J at -20°C |
Note: Yield strength decreases slightly as the material thickness increases due to the effects of the rolling and cooling process.
4. Typical Applications
S355J2H tubes are used in critical structures where strength, durability, and safety are paramount.
Building and Construction: Steel frames for buildings, halls, stadiums, and bridges.
Heavy Equipment: Chassis, booms, and structural members for cranes, excavators, and agricultural machinery.
Support Structures: Towers for wind turbines, communication masts, and offshore platforms.
Material Handling: Frames for conveyor systems and heavy-duty storage racks.
General Mechanical Engineering: For any application requiring robust, welded tubular structures.
5. Comparison with Other Grades
vs. S355J2H (Cold-Formed): The cold-formed equivalent is S355J2H according to EN 10219. While the chemical and mechanical properties are similar, hot-finished sections generally have better corner properties (more uniform thickness and strength) and are available in thicker walls and larger sizes.
vs. S355J0H: The "J0" grade has lower impact toughness requirements (tested at 0°C instead of -20°C). S355J2H is preferred for colder environments.
vs. S355K2H: The "K2" grade has higher impact toughness requirements (tested at -20°C but with a higher minimum energy, typically 40J or more). It is used for more critical applications.
Summary
S355J2H is a versatile, high-strength, and tough structural steel tube. Its well-defined properties, governed by the EN 10210 standard, make it a reliable and preferred choice for engineers and designers across Europe and internationally for constructing safe and efficient steel structures.
