S355J2 and S355K2 are both EN 10025-2 structural steels with a minimum yield strength of 355 MPa, but their key difference lies in their impact toughness at low temperatures: S355J2 requires 27 Joules (J) at -20°C, while S355K2 requires 40 Joules (J) at -20°C, making S355K2 tougher and better for high-impact, colder environments.
S355J2 and S355K2 steel plates chemical composition:
| 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 |
S355J2 and S355K2 steel plates Mechanical properties:
| ReH Minimum Yield strength (MPa ) | R m (MPa) | ||||||||||||
| for nominal thickness(mm) | for nominal thickness (mm) | ||||||||||||
| <16 | =>16 | >40 | >63 | >80 | >100 | >150 | >200 | >250 | <3 | =>3 | >100 | >150 | >250 |
| ≤ 40 | ≤63 | ≤ 80 | ≤100 | ≤150 | ≤200 | ≤250 | ≤400 | ≤ 100 | ≤150 | ≤250 | ≤400 | ||
| 355 | 345 | 335 | 325 | 315 | 295 | 285 | 275 | 265 | 510-680 | 470-630 | 450-600 | 450-600 | 450-600 |
However, what is the difference between S355J2 and S355K2 steel plates? It mainly lies in their impact test:
J2 symbol Charpy V-Notch Impact Tested Longitudinal 27 Joules at -20 ˚C under 150mm thickness.
K2 symbol Charpy V-Notch Impact Tested Longitudinal 40 Joules at -20 ˚C max 100mm thickness.
S355K2 steel plates Charpy V-Notch Impact Tested Longitudinal 40 Joules at -20 ˚C, S355J2 steel plates Charpy V-Notch Impact Tested Longitudinal 27 Joules at -20 ˚C under 150mm thickness. S355K2 steel plates are good in highly impact under low temperature condition projects.
