Both S355JR and S355J2+N belong to the EN 10025 structural steel family, specifically within the group of non-alloy structural steels. These grades are widely used in civil engineering and construction, where steel components serve as load-bearing elements in steel structures or as reinforcement in composite and reinforced concrete systems.
Key Differences Between S355JR and S355J2+N
The distinguishing factor between these two steel grades lies in the second part of their designation, which refers to their impact toughness (resilience).
Impact toughness represents the amount of energy a steel can absorb during elastic deformation before fracture.
It is a critical property for structures exposed to dynamic loads, shocks, or low-temperature environments.
Impact Test Requirements
S355JR
Minimum impact energy: 27 J
Test temperature: +20°C (room temperature)
S355J2+N
Minimum impact energy: 27 J
Test temperature: –20°C
This means S355J2+N offers superior performance in cold conditions, making it more suitable for outdoor structures or regions with low ambient temperatures.
Significance of "+N" Normalizing
The "+N" designation indicates that the steel has been supplied in the normalized or normalized-rolled condition. Normalizing is a heat treatment process that refines and homogenizes the steel's grain structure, resulting in:
Improved toughness and strength
More uniform mechanical properties
A lower ductile-to-brittle transition temperature
Enhanced resistance to brittle fracture
This treatment significantly improves structural reliability, especially in demanding or low-temperature environments.
Typical Applications of S355JR and S355J2+N
Construction steels such as S355JR and S355J2+N are valued for their:
Excellent toughness
Balanced weldability and machinability
Adequate hardness and heat resistance
Structural safety and durability
They are commonly used in:
Building frames and steel structures
Bridges and motorway infrastructure
Machinery and heavy equipment
Shipbuilding and offshore structures
These steels allow engineers to design efficient, open structures with fewer support elements, maximizing usable space while maintaining high safety standards.
| Property | S355JR | S355J2+N |
|---|---|---|
| Impact Energy | 27 J | 27 J |
| Test Temperature | +20°C | –20°C |
| Delivery Condition | As rolled | Normalized (+N) |
| Low-temperature performance | Standard | Superior |
S355J2+N is the preferred choice when low-temperature toughness and structural reliability are critical, while S355JR is well suited for standard structural applications under normal environmental conditions.
What is S355JR equivalent to?
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.
What is material specification S355JR?
Grade S355JR has a minimum yield strength of 355 MPa. The impact energy at a room temperature of 20°C is at least 27 joules.
What is the difference between S275JR and S355JR?
S275JR: Offers a minimum yield strength of 275 MPa for thicknesses up to 16 mm. This makes it suitable for applications where moderate strength is sufficient. S355JR: Provides a higher minimum yield strength of 355 MPa for thicknesses up to 16 mm, making it ideal for projects requiring greater load-bearing capacity.
What material is EN 10025 2 S355JR?
S355JR steel is one mainly of Carbon and low alloy steel, S355JR steel is a type of steel sheet under EN standard which is used to build ship, bridge, belongs to high strength sheet. EN 10025-2 is the Standard Specification Technical Delivery Conditions for Non-Alloy Structural steels.
Is S235JR a mild steel?
S235jr steel is a mild steel, its carbon composition below 2%. So the S235JR Mild steel have very good welding performance. For S235JR, we supply the steel plate, steel round bar, steel hexagonal bar, flat bar, square bar and pipe.