ASTM A572 Gr.55 is a high strength low alloy steel (HSLA steel) formulated for structural applications requiring higher yield strength than Grade 50, while maintaining excellent ductility and formability. Alloyed with elements such as columbium, vanadium, and sometimes copper, it provides superior resistance to fatigue and impact. Commonly used in A572 Grade 55 bridge steel plate for long-span structures and A572 structural steel in high-rise buildings, this grade excels in environments with moderate corrosion exposure.
1.ASTM A572 Gr.55 Chemical Composition
The chemical composition of ASTM A572 Gr.55 is optimized for strength and corrosion resistance, with tight controls on impurities. Below is a detailed table of its composition:
|
Element |
Composition (%) |
|---|---|
|
Carbon (C) |
≤ 0.25 |
|
Manganese (Mn) |
≤ 1.35 |
|
Phosphorus (P) |
≤ 0.04 |
|
Sulfur (S) |
≤ 0.05 |
|
Silicon (Si) |
≤ 0.40 |
|
Vanadium (V) |
0.01-0.15 |
|
Columbium (Nb) |
0.005-0.05 |
|
Copper (Cu) (when specified) |
≥ 0.20 |
2. ASTM A572 Gr.55 Mechanical Properties
|
Property |
Value |
|---|---|
|
Yield Strength (Min) |
380 MPa (55 ksi) |
|
Tensile Strength |
485 MPa (70 ksi) min |
|
Elongation (in 200mm) |
≥ 17% |
|
Elongation (in 50mm) |
≥ 20% |
|
Charpy Impact Toughness (at 0°C, optional) |
≥ 27 J |
These ASTM A572 Grade 55 mechanical properties provide a balance of high yield for load-bearing and sufficient elongation for forming, outperforming standard carbon steels in fatigue-prone applications like bridges and cranes.
3. Equivalent Grades
ASTM A572 Gr.55 aligns with several global standards, facilitating easy substitution in multinational projects. The table below compares common equivalents:
|
Standard |
Equivalent Grade |
|---|---|
|
EN 10025 |
S355J2 / S355K2 |
|
DIN |
St52-3N |
|
JIS |
SM490B / SM490YB |
|
GB |
Q345C / Q345E |
|
BS |
50D / 50E |
These ASTM A572 Grade 55 equivalent grades ensure compatibility across regions, with EN S355J2 offering similar cold-weather performance for European specifications.
4. ASTM A572 Gr.55 vs ASTM A36 Steel - Strength and Application Differences
When comparing ASTM A572 Gr.55 vs A36 steel, the former's higher yield strength (380 MPa vs 250 MPa) and alloy content stand out. A36 is a basic carbon steel suitable for general fabrication, but lacks the columbium and vanadium in Gr.55, which improve corrosion resistance and weldability. Gr.55 allows for thinner sections in designs, reducing weight and costs in bridges or machinery, while A36 is more economical for low-load uses.
5. Applications
The versatility of ASTM A572 Grade 55 steel plate extends to various industries. In bridge construction, it's used as A572 Grade 55 bridge steel plate for beams and supports in long-span designs. High-rise buildings benefit from its role as A572 structural steel in seismic frames and columns. Construction machinery, such as excavators and loaders, relies on its impact resistance. Additional applications include power transmission towers, railcar components, and agricultural equipment frames.
6. Specification
|
Dimension |
Available Range |
|---|---|
|
Thickness |
6mm - 200mm |
|
Width |
1500mm - 3200mm |
|
Length |
Up to 18000mm |
These dimensions provide versatility for custom projects, with options for precise cutting and edge preparation.
