S235J0 and S420J0 are non-alloy structural steel grades specified under EN 10025-2, the European standard for hot-rolled structural steels . Both grades are classified as non-alloy quality steels and share the same designation logic: "S" indicates structural steel, the number represents minimum yield strength (MPa) at ≤16mm thickness, and "J0" signifies guaranteed Charpy V-notch impact energy of 27J at 0°C .
Key Differences:
Strength Level: S420J0 provides approximately 79% higher minimum yield strength (420 vs 235 MPa) where applicable, enabling substantial weight reduction in long product applications .
Product Form Applicability: This is the most fundamental distinction. S235J0 is widely available as plates, sheets, strip, and long products . S420J0 is restricted to long products only (beams, channels, bars, sections) and NOT PRODUCED AS PLATE under EN 10025-2 . Any plate requirement for 420 MPa yield strength must specify S420NL (Part 3) or S420ML (Part 4) .
Ductility and Formability: S235J0 offers significantly superior elongation (26% vs 17%), far better cold bending performance, and is expressly suitable for cold flanging (available as S235J0C) .
Weldability: S235J0's lower carbon and CEV provide exceptional weldability with zero preheat requirements. S420J0 long products require more careful welding procedures due to higher carbon equivalent .
Applications: S235J0 is extensively used for light to medium load-bearing structures, building frameworks, bridges, mechanical components (shafts, pins, supports), and general fabrication where moderate strength, excellent weldability, and cost-effectiveness are prioritized . S420J0 (long products) serves higher-stressed structural components where enhanced strength justifies premium cost, though fine-grain variants (S420N/NL, S420M/ML) are overwhelmingly preferred for demanding applications requiring both high strength and assured toughness .
Availability and Cost: S235J0 is universally stocked, cost-effective, and available in all product forms. S420J0 plate form does not exist under EN 10025-2; purchasers requiring 420 MPa yield plates must source S420NL or S420ML at significantly higher cost.
Mechnical property for S235J0 steel plate:
| Thickness (mm) | |||||||||
| S235J0 | ≤ 16 | > 16 ≤ 40 | > 40 ≤ 63 | > 63 ≤ 80 | > 80 ≤ 100 | > 100 ≤ 150 | > 150 ≤ 200 | > 200 ≤ 250 | > 250 |
| Yield strength (≥Mpa) | 235 | 225 | 215 | 215 | 215 | 195 | 185 | 175 | 175 |
| < 3 | ≥ 3 ≤ 100 | > 100 ≤ 150 | > 150 ≤ 250 | > 250 | |||||
| Tensile strength (Mpa) | 360-510 | 360-510 | 350-500 | 340-490 | 340-490 | ||||
Mechnical property for S420J0 steel plate:
| Grade |
Thk(mm) |
Yield Strength |
Tensile Strength |
Elongation in 2 in. |
|
MPa |
MPa |
% |
||
|
S420J0 |
≦16 |
450 |
550-720 |
17 |
|
>16, ≦100 |
410 |
|||
|
>100 |
380 |
530-700 |
Chemical composition for S235J0 steel plate
| Main chemical elements composition of S235J0 steel plate | |||||||
| Thickness(mm) | C | Si | Mn | P | S | N | Cu |
| T≤16 | 0.17 | ... | 1.40 | 0.030 | 0.030 | 0.012 | 0.55 |
| 16<T≤40 | 0.17 | ||||||
| 40<T | 0.17 | ||||||
Chemical composition for S420J0 steel plate
|
Grade |
Thk(mm) |
C |
Mn |
Si |
P |
S |
N |
Cu |
|
S420J0 |
≦40 |
0.2 |
1.7 |
0.55 |
0.03 |
0.03 |
0.025 |
0.55 |
|
>40 |
0.22 |
