The main difference between S355JR and S355J2 steel is the impact test temperature. S355JR is tested for impact toughness at a room temperature of +20°C, making it suitable for mild conditions, while S355J2 requires testing at a sub-zero temperature of -20°C, making it better for cold environments.
Both grades share the same minimum yield strength of 355 MPa but offer different levels of low-temperature performance.
The main difference between S355JR and S355J2 steel is the impact test temperature. S355JR is tested for impact toughness at a room temperature of +20°C, making it suitable for mild conditions, while S355J2 requires testing at a sub-zero temperature of -20°C, making it better for cold environments. Both grades share the same minimum yield strength of 355 MPa but offer different levels of low-temperature performance.
S355JR
Impact Test:Tested at +20°C.
Application:Suited for general structural applications in mild, warmer environments.
Performance:Lacks the enhanced low-temperature resistance of the J2 grade.
S355J2
Impact Test:Tested at -20°C, requiring a specific Charpy V-notch impact test at this colder temperature.
Application:Preferred for cold environments, offshore platforms, arctic applications, and other situations requiring superior sub-zero performance.
Performance:Offers better adaptability to low-temperature work conditions than S355JR due to its lower impact test temperature.
The "J" in the designation signifies that the steel has undergone a Charpy impact test, and the subsequent number (R or 2) indicates the temperature at which this test was conducted.
While both grades have a minimum yield strength of 355 MPa, the J2 designation provides a crucial advantage for applications exposed to colder conditions.
What is the difference between J2 and JR? Can they be used as substitutes for each other?
J2 and JR refer to the material's sub-grade - its fracture toughness - which is measured in joules [J] of a material's toughness at a particular temperature.
J2 is a material with a minimum of 27 joules at -20C while JR is a material with a minimum of 27 Joules at +20C (room temperature).
A JR material is normally used in an internal environment whereas a J2 is for external use.
If J2 is required you must not substitute JR.
Chemical composition difference between S355JR and S355J2 steel: %
| Grade | C | Si | Mn | P | S | Cu | N |
| S355JR | 0.27 max | 0.60 max | 1.70 max | 0.045 max | 0.045 max | 0.60 max | 0.014 max |
| S355J2 | 0.24 max | 0.60 max | 1.70 max | 0.035 max | 0.035 max | 0.60 max | 0.014 max |
Mechanical properties difference between S355JR and S355J2 steel:
| Grade | Yield strength ReH/(N/mm2) (t≤16mm) min | Tensile strength Rm/(N/mm2) (3mm≤t≤16mm) | Elongation A/%(3mm≤t≤40mm) min | Charpy V test | |
| Temperature/℃ | Impact energy (Longitudinal)/J min | ||||
| S355JR | 355 | 450-680 | 22 | 20 | 27 |
| S355J2 | 355 | 450-680 | 22 | -20 | 27 |
Differences between S355JR and S355J2+N steel
The second part of the abbreviation of this particular type of structural steel indicates the resilience value. Resilience indicates the quantity of energy that is absorbed by the alloy during an elastic deformation process. In other words, a material is able to absorb energy and in doing so resists external dynamic forces that instead push the steel to break.
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. Instead the N indicates that the steel has undergone the normalisation process, a heat treatment by which the crystalline grain of the steel is refined and made more uniform, increasing the strength of the material and moving the ductile-brittle transition.
Which to choose, S355JR or S355J2?
When choosing between S355JR and S355J2, it's essential to understand the differences in their mechanical properties and suitability for specific applications.
Impact Toughness (Charpy V-Notch Test):
S355JR: Tested at 20°C with a minimum Charpy impact energy of 27 Joules.
S355J2: Tested at -20°C with a minimum Charpy impact energy of 27 Joules, making it more suitable for colder conditions. The "J2" designation indicates it has higher resilience at low temperatures.
Application Suitability:
S355JR: Commonly used in structural applications, construction, and fabrication where ambient temperatures are moderate.
S355J2: Preferred for projects exposed to lower temperatures or requiring better impact resistance in cold climates. It is often chosen for offshore structures, bridges, and heavy-duty parts in colder regions.
Welding and Processing:
Both grades are well-suited for welding and offer good machinability and formability. S355J2 may be marginally easier to weld due to its slightly improved toughness.
Which to Choose?
For applications in standard or mild temperatures, where cost is a priority, S355JR is typically sufficient.
For applications in colder climates or where impact toughness is critical, S355J2 is preferable.
In summary, the choice depends on environmental conditions and the required toughness.
4 Different Types of Construction Steel From GNEE STEEL
S460 High-Strength Structural Steel
S460 construction steel has a high strength-to-weight ratio and is often used in high-rise buildings. The S460 can be easily welded as a result of its reduced carbon content, has high tensile strength and can withstand temperatures as low as -50oC.
The S460 material is available in two variations: S460NL and S460ML. The S460NL is manufactured with normalized material, whereas the S460ML is made via a thermo-mechanically controlled process (TMCP).
The S460 steel we offer is versatile and reliable, and can be produced in a range of sizes from 6mm to 80mm thick, up to three meters wide and up to 12 meters in length.
S355 Structural Steel and Plate
S355 is a structural grade steel that is often used in the construction and engineering industries. A large number of S355 steels are available at Masteel, but we can provide an overview of the S355JR, S355AR and S355J2/K2+N.
S355JR has a yield strength of at least 355N/mm2 and has been through the charpy impact test, which explains the JR allocation to the name as the test was carried out at 27J (Joules) at room temperature.
S355AR has the same yield strength as the S355JR, but the AR denotes it is sold in 'as rolled condition'.
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.
S275 Structural Grade Steel
S275 is a low carbon steel that is frequently used in building bridges and multi-story buildings. It is also used in the oil and gas industry as well as in components required in vehicles and heavy equipment.
The minimum yield strength of S275 is 275N/mm2, it is suitable for welding and is used in a range of construction applications. The two options of the S275 steel are: S275JR, which has been subjected to the Charpy impact test at 27J(Joules) at room temperature, and the S275AR, which is supplied in 'as rolled condition'.
S235 Structural Steel Plate
There are multiple variations of S235 available, but typically it is supplied as untreated or in normalized condition. S235 is commonly used to manufacture rolled products which are then used in steel structures. Not only are they reliably strong, but they are also suitable for welding. However, it is worth noting that the tensile strength of S235 wavers if temperatures exceed 600oC.
S235 is most frequently supplied as S235JR, as it has undergone the Chary impact test at 27J (Joules) at room temperature, and the S235AR, which is supplied in 'as rolled condition'.
