Q620E is a core grade of low-alloy high-strength structural steel, mainly complying with Chinese standards such as GB/T 1591-2018 (Low-Alloy High-Strength Structural Steels), GB/T 16270-2009 (Quenched and Tempered High-Strength Structural Steel Plates), and GB/T 5310-2023 (Technical Specification for Steel Pipes for Special Equipment).
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Grade |
Chemical requirement or element Max % |
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|
|
C |
Si |
Mn |
P |
S |
Cu |
Cr |
Ni |
Mo |
B |
V |
Nb |
Ti |
|
|
Q620E |
0.2 |
0.8 |
1.7 |
0.020 |
0.010 |
0.5 |
1.5 |
2 |
0.7 |
0.005 |
0.12 |
0.06 |
0.05 |
|
Q620E Property in tensile and yield strength, and impact test requirement
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Grade |
Property |
Impact test |
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|
Q620E |
Yield Mpa Min |
Tensile Mpa |
Elongation |
Min J |
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|
Thickness mm |
Thickness mm |
Degree |
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|
50 |
50-100 |
100-150 |
50 |
50-100 |
100-150 |
% |
0 |
-20 |
-40 |
-60 |
|
|
620 |
580 |
560 |
700-890 |
650-830 |
15 |
|
|
37 |
|
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Processing Adaptability of Q620E
Q620E balances high strength with manageable cold forming: while thicker plates may require mild preheating (80–100°C) to avoid cracking, its fine-grained tempered bainite microstructure allows tight bending radii (≥3x plate thickness) and multi-pass forming without work hardening. Weldability is another highlight: its low carbon equivalent (≤0.45%) pairs with ultra-low-hydrogen consumables to produce defect-free joints, even for thick-section welds in offshore or polar structures. Post-weld stress relief (200–250°C) further preserves its -40°C toughness, critical for long-term performance in temperature-fluctuating environments.
Field Performance of Q620E
Q620E excels in corrosion resistance when paired with proper surface treatments: shot blasting to Sa2.5 grade, followed by a multi-layer epoxy-polyurethane coating, enables it to withstand salt spray (common in offshore platforms) and de-icing chemicals (used on cold-region bridges) for 30+ years. Its Z-direction (thickness-wise) strength (Z15–Z35 grades) also prevents lamellar tearing in welded components like crane booms or wind turbine towers, a failure mode that plagues lesser high-strength steels under through-thickness loads.
What are the properties of Q620E hot-rolled seamless pipes?
They have low carbon content, are strengthened by micro-alloys, have a yield strength of 620MPa, and the demand in fields such as wind power will surge.
What are the applications of Q620E seamless pipes?
They are suitable for fields such as oil and natural gas, and have typical applications in high-pressure transportation, supercritical boilers, and offshore platforms.
What is the difference between Q620ME and Q620E square and rectangular pipes?
Both belong to high-strength steel, but they differ in microstructure and performance, as well as in application scenarios and corrosion resistance.