SM490A and SM490B are Japanese (JIS G3106) structural steel grades with the same minimum tensile strength (490 MPa) but differ in their toughness requirements, specifically Charpy impact testing: SM490B requires impact testing (e.g., 27J at 0°C), while SM490A typically has no specified impact test, making B better for colder or critical applications, whereas A offers good general weldability and strength at potentially lower cost.
Chemical Composition
|
SM490AChemical Composition |
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|
Grade |
The Element Max (%) |
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|
C |
Si |
Mn |
P |
S |
Cu (min) |
|
|
SM490A |
0.20-0.22 |
0.55 |
1.65 |
0.035 |
0.035 |
- |
|
SM490BChemical Composition |
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|
Grade |
The Element Max (%) |
|||||
|
C |
Si |
Mn |
P |
S |
Cu (min) |
|
|
SM490B |
0.18-0.20 |
0.55 |
1.65 |
0.035 |
0.035 |
- |
Mechanical Property
|
Grade |
SM490AMechanical Property |
|||
|
Thickness |
Yield |
Tensile |
Elongation |
|
|
SM490A |
mm |
Min Mpa |
Mpa |
Min % |
|
t≦16 |
325 |
490-610 |
17 |
|
|
16<t≦90 |
295-315 |
490-610 |
23 |
|
|
Grade |
SM490BMechanical Property |
|||
|
Thickness |
Yield |
Tensile |
Elongation |
|
|
SM490B |
mm |
Min Mpa |
Mpa |
Min % |
|
t≦16 |
325 |
490-610 |
17 |
|
|
16<t≦90 |
295-315 |
490-610 |
23 |
|
Key Differences
Impact Toughness: SM490B demands low-temperature impact energy absorption (like 27 Joules at 0°C), ensuring better performance in cold conditions or seismic zones, while SM490A usually has no such requirement.
Application: SM490A is for general construction needing strength and weldability; SM490B offers enhanced toughness for more demanding uses like bridges, ships, or structures in colder climates.
Cost/Availability: SM490A is generally more readily available and costs less than the tougher SM490B grade.
