Based on its chemical composition, S355JR Channel Bar is classified as a low-alloy structural steel section. Its total alloying element content is higher than that of conventional carbon steel, yet lower than that of high-alloy steels, providing an optimal balance of strength, weldability, and cost efficiency.
This balanced alloy design makes S355JR channel steel particularly suitable for load-bearing structural applications requiring both mechanical strength and reliable fabrication performance.
Chemical Composition (Maximum Values)
| Grade | C (%) | Si (%) | Mn (%) | P (%) | S (%) | N (%) | Cu (%) |
|---|---|---|---|---|---|---|---|
| S355JR Channel Bar | 0.27 | 0.60 | 1.70 | 0.045 | 0.045 | 0.014 | 0.60 |
Maximum Content of Alloying Elements
Carbon (C) ≤ 0.27%
Ensures high strength while maintaining good weldability for channel sections.
Manganese (Mn) ≤ 1.70%
Improves tensile strength, toughness, and load-bearing capacity of the channel bar.
Phosphorus (P) ≤ 0.045%
Strictly controlled to preserve ductility and impact performance.
Sulfur (S) ≤ 0.045%
Kept at low levels to reduce brittleness and ensure stable welding quality.
Nitrogen (N) ≤ 0.014%
Controlled to maintain toughness and prevent strain aging.
Silicon (Si) ≤ 0.60%
Acts as a deoxidizer and contributes to improved strength.
Copper (Cu) ≤ 0.60%
Enhances atmospheric corrosion resistance, especially for outdoor channel bar applications.
Influence of Chemical Composition
The optimized chemical composition of S355JR Channel Bar provides high yield strength, excellent toughness, and reliable fabrication performance. These characteristics allow the channel bar to withstand heavy static and dynamic loads while maintaining dimensional stability.
As a result, S355JR channel steel is widely used in structural and heavy-duty frameworks, including:
- Building and bridge structural frames
- Support structures for construction and mining equipment
- Crane booms, lifting frames, and load-bearing supports
- Industrial platforms and machinery bases
- Transportation and infrastructure structural components
The combination of high strength, durability, and fabrication versatility makes S355JR Channel Bar a preferred choice for modern structural engineering applications.
What does S355JR mean?
S355JR is a grade of low-carbon steel commonly used in structural applications. It is part of the 'S' family of steels, which includes S235, S275, and S355 grades. The "JR" designation means that the material has been subjected to a Charpy V-notch impact test at 208℃ and has a minimum impact strength of 27 Joules.
What is equivalent to S355JR steel?
S355JR equivalent grades have very close chemical composition and mechanical properties to that of S355JR steel. Both the S355JR equivalent grades Q345B, A572 Gr 50, ST52-3, SM490B and S355JR steel are main products of Gnee steel.
What is the difference between S355J2 and S355JR?
S355J2/K2+N is the same steel as S355JR but it is supplied in a normalized condition and underwent a Charpy test at 40J (Joules) at -20oC. Any steels that are put through the Charpy impact or 'V' notch test will have the letters 'J2', 'K2', 'JR' or 'JO', which denotes their material toughness.
What does S355JR stand for?
S355 structural grade (S) carries minimum yield strength of 355 N/mm²m, the JR designation confirms that the steel has undergone longitudinal Chary V-Notch impact testing at 27J (Joules) at room temperature. Other Charpy designations include J0, J2 and K2.
What is S355 steel used for?
S355 is often used in the most demanding environments such as the offshore industry. S355, S355JR, S355J2, S355J2+N steel in plate, round bar, flat bar and blocks. S355 steel is a low carbon steel whose specifications offer high yield strength.