SS490 and SS540 are Japanese standard structural steels (JIS G3101) differing primarily in strength, with SS540 offering significantly higher yield and tensile strength than SS490, making it suitable for heavier loads, while SS490 is a versatile, general-purpose structural steel; both provide good weldability but SS540's increased strength comes from its higher alloy content (like manganese), requiring attention to welding procedures for thicker plates.
Chemical Composition
| Grade | C | Mn | P | S |
|---|---|---|---|---|
| SS540 | 0.30 | 1.60 | 0.04 | 0.04 |
| Grade | C≤ 16mm max | C>16mm max | Si max |
Mn max | P max. |
S max. |
| SS490 | 0.24 | 0.24 | 0.55 | 1.60 | 0.045 | 0.045 |
Mechanical propertie
|
Grade |
Thickness |
Yield |
Tensile |
Elongation |
|
SS540 |
mm |
Min Mpa |
Mpa |
Min % |
|
≤5 |
400 |
540 |
16 |
|
|
5--≤16 |
13 |
|||
|
>16 |
390 |
17 |
|
Mechanical propertie |
||||||||
|
SS490 |
Yield strength (N/MM2) |
Tensile strength (N/MM2) |
Elongation |
|||||
|
TH(MM) |
≤16 |
>16≤40 |
>40≤100 |
>100 |
490-610 |
15 |
||
|
|
285 |
275 |
255 |
245 |
||||
Key Differences
Strength:
SS490: Lower yield and tensile strength, suitable for general structures.
SS540: Higher strength, with tensile strength around 540 MPa and yield strength ≥355 MPa, ideal for heavy-duty applications like bridges, heavy machinery, and marine structures.
Composition: SS540 has higher manganese content (≤1.60%) and slightly different limits for carbon, silicon, phosphorus, and sulfur to achieve its higher strength.
Applications: SS490 is for general construction, while SS540 is for demanding, high-load scenarios.
Mechanical Properties: SS540 provides better load-bearing capacity due to its higher strength, though SS490 remains a strong, reliable choice.
