Both S275ML and S420ML are thermomechanically rolled (TMCP) fine-grain structural steel grades specified under EN 10025-4, designed for welded structures requiring high toughness, excellent weldability, and guaranteed low-temperature impact performance . The "L" designation signifies enhanced toughness with Charpy V-notch impact testing at -50°C (minimum 27J longitudinal), compared to the -20°C requirement for non-L grades .
S275ML has a minimum yield strength of 275 MPa (≤16mm thickness), tensile strength of 370-530 MPa, and minimum elongation of 24% . Its maximum carbon equivalent (CEV) is 0.34% for thicknesses ≤40mm, ensuring excellent weldability with minimal preheating . Chemical composition limits include C ≤0.13%, Mn ≤1.50%, and microalloying elements (Nb ≤0.05%, V ≤0.08%) .
S420ML offers substantially higher strength with minimum yield of 420 MPa (≤16mm), tensile strength of 520-680 MPa, but lower elongation of 19% . Its CEV is higher at 0.43% (≤16mm), reflecting increased alloy content: Mn ≤1.70%, Ni ≤0.80%, and V ≤0.12% .
Key Differences:
Strength Level: S420ML provides approximately 53% higher yield strength (420 vs 275 MPa), enabling significant weight reduction in structural designs .
Chemical Composition: S420ML permits higher carbon (0.16% vs 0.13%), manganese (1.70% vs 1.50%), and nickel (0.80% vs 0.30%), contributing to its enhanced strength .
Ductility and Formability: S275ML offers superior ductility with 24% elongation versus 19% for S420ML, and better cold bending performance (2× thickness vs 4× thickness radius) .
Weldability: S275ML's lower CEV (0.34% vs 0.43%) provides even easier welding characteristics with virtually no preheat requirements .
Applications: S275ML suits general structural fabrication, storage tanks, and moderate-load components in low-temperature environments. S420ML is preferred for highly stressed structures such as offshore platforms, cranes, heavy machinery, and Arctic infrastructure where higher strength-to-weight ratios justify reduced section sizes .
Chemical composition for S275ML STEEL PLATE
|
EN10025-4 S275ML Chemical Composition |
|||||||
|
Grade |
The Element Max (%) |
||||||
|
C |
Si |
Mn |
P |
S |
Al |
N |
|
|
S275ML |
0.15 |
0.55 |
1.60 |
0.030 |
0.025 |
0.015 |
0.017 |
|
Nb |
V |
Ti |
Cu |
Cr |
Ni |
Mo |
|
|
0.06 |
0.10 |
0.06 |
0.60 |
0.35 |
0.35 |
0.13 |
|
Chemical composition for S420ML STEEL PLATE
| Main chemical elements composition of S420ML STEEL PLATE | ||||||
| C | Si | Mn | P | S | Nb | V |
| 0.16 | 0.50 | 1.70 | 0.025 | 0.020 | 0.05 | 0.12 |
| Al(total) | Ti | Cr | Ni | Mo | Cu | N |
| ≥0.02 | 0.05 | 0.30 | 0.80 | 0.20 | 0.55 | 0.025 |
Mechanical properties for S275ML STEEL PLATE:
|
Grade
|
Thickness |
Yield Strength |
Tensile Strength |
Elongation |
Impact Energy |
|
(mm) |
MPa (min) |
MPa |
% (min) |
(KV J) (min) |
|
|
|
|
|
|
-50 degree |
|
|
S275ML |
≤ 16 |
275 |
370-530 |
24 |
27 |
|
16> to ≤40 |
265 |
370-530 |
24 |
27 |
|
|
40> to ≤63 |
255 |
350-510 |
24 |
27 |
|
|
63> to ≤80 |
245 |
350-510 |
24 |
27 |
|
|
80> to ≤100 |
245 |
350-510 |
24 |
27 |
|
|
100> to ≤120 |
240 |
350-510 |
24 |
27 |
Mechnical property for S420ML STEEL PLATE:
| Thickness (mm) | ||||||
| S420ML | ≤ 16 | > 16 ≤ 40 | > 40 ≤ 63 | > 63 ≤ 80 | > 80 ≤ 100 | > 100 |
| Yield strength (≥Mpa) | 420 | 400 | 390 | 380 | 370 | 365 |
| ≤ 40 | > 40 ≤ 63 | > 63 ≤ 80 | > 80 ≤ 100 | > 100 | ||
| Tensile strength (Mpa) | 520-680 | 500-660 | 480-640 | 470-630 | 460-620 | |
