S355J2 and S355JR are both high-strength structural steels with a minimum yield strength of 355 MPa, but their key difference lies in their low-temperature impact toughness requirements: S355JR (JR = Room Temp) is tested at +20°C (27 Joules), while S355J2 (J2 = -20°C) is tested at -20°C, making S355J2 better suited for cold climates, offshore platforms, and other demanding environments requiring superior low-temperature performance. Both offer excellent weldability, with S355J2 providing better cold-weather toughness for applications like wind towers, bridges, and heavy machinery.
Chemical Composition of S355J2
| Thickness (mm) | C | Mn | Si | P | S | N | Cu |
| under 40 | 0.2 | 1.6 | 0.55 | 0.025 | 0.025 | - | 0.55 |
| >40 | 0.22 |
Chemical Composition of S355JR
| Nominal thickness =< 30(mm) CEV max = 0.45 |
| C | Si | Mn | P | S | N | Cu | CEV |
| max 0.24 | max 0.55 | max 1.6 | max 0.04 | max 0.04 | max 0.012 | max 0.55 | max 0.47 |
Mechanical Properties of S355J2
|
Property |
Value |
|---|---|
|
Yield Strength (min) |
355 MPa |
|
Tensile Strength |
470–630 MPa |
|
Elongation (min, in 200 mm) |
20% |
|
Impact Toughness (Charpy V-notch, min) |
27 J at -20°C |
|
Hardness (HB, typical) |
150–200 HB |
|
Density |
7.85 g/cm³ |
|
Modulus of Elasticity |
210 GPa |
|
Poisson's Ratio |
0.3 |
Mechanical properties of steel S355JR
| Nominal thickness (mm): | to 3 | 3 - 100 | 100 - 150 | 150 - 250 |
| Rm - Tensile strength (MPa) Flat and long products | 510-680 | 470-630 | 450-600 | 450-600 |
| Nominal thickness (mm): | to 16 | 16 - 40 | 40 - 63 | 63 - 80 | 80 - 100 | 100 - 150 | 150 - 200 | 200 - 250 |
| ReH - Minimum yield strength (MPa) Flat and long products | 355 | 345 | 335 | 325 | 315 | 295 | 285 | 275 |
| KV - Impact energy (J) longitud., | -20° 27 |
0° 27 |
+20° 27 |
| Nominal thickness (mm): | to 1 | 1 - 1.5 | 1.5 - 2 | 2 - 2.5 | 2.5 - 3 |
| A - Min. elongation Lo = 80 mm (%) parallel, | 14 | 15 | 16 | 17 | 18 |
| Nominal thickness (mm): | 3 - 40 | 40 - 63 | 63 - 100 | 100 - 150 | 150 - 250 |
| A - Min. elongation Lo = 5,65 √ So (%) parallel, | 22 | 21 | 20 | 18 | 17 |
S355JR Steel Plate
Impact Test Temp: +20°C (room temperature).
Application: General construction, large machinery, frameworks, and structures not exposed to severe cold.
Key Feature: Good general strength and weldability.
S355J2 Steel Plate
Impact Test Temp: -20°C (low temperature).
Application: Colder regions, offshore structures, wind energy, pipelines, and heavy equipment where low-temp toughness is critical.
Key Feature: Superior low-temperature impact resistance and toughness.
Key Similarities & Differences
Strength: Both have the same minimum yield strength (355 MPa) and similar tensile strength ranges.
Composition: Largely similar low carbon content, ensuring good weldability.
The "J" Code: The 'J' indicates impact testing; 'R' is +20°C, '2' is -20°C.
Performance: S355J2 offers better performance and reliability in cold conditions than S355JR.
