Q620E is a premium low-alloy high-strength structural steel, engineered to deliver exceptional performance in scenarios where ultra-low temperatures and heavy loads coincide. Classified under China's national standards, it is typically delivered in a quenched and tempered (QT) condition, combining 620MPa-level yield strength with reliable toughness at -40℃-a combination that makes it irreplaceable for projects in frigid regions and high-stress environments.
Q620E Chemical compositionMax % of the Product analysis of grade
|
C |
Si |
Mn |
P |
S |
Nb |
V |
Ti |
|
0.18 |
0.60 |
2.00 |
0.025 |
0.020 |
0.11 |
0.12 |
0.20 |
|
Cr |
Ni |
Cu |
N |
Mo |
B |
Als min |
|
|
1.00 |
0.80 |
0.80 |
0.015 |
0.30 |
0.004 |
0.015 |
|
Q620E Yield strength
|
Nominal thickness (mm) |
To 16 |
16-40 |
40-63 |
63-80 |
80- 100 |
100- 150 |
150- 200 |
200- 250 |
250- 400 |
|
ReH - Minimum yield strength (MPa) |
620 |
600 |
590 |
570 |
- |
- |
- |
- |
- |
Q620E Tensile Strength
|
Nominal thickness (mm) |
To 40 |
40-63 |
63-80 |
80-100 |
100-150 |
150-250 |
250-400 |
|
ReH - Minimum yield strength (MPa) |
710-880 |
690-880 |
670-860 |
- |
- |
- |
- |
Q620E Impact Test degree and energy
|
|
Min Energy Nominal thickness |
||
|
Temperature ℃ |
-40 |
||
|
Thickness (mm) |
12-150 |
150-250 |
250-400 |
|
Notch impact test. Min. absorbed energy |
31 |
- |
- |
Equivalent grades of grade Q620E
- Q620E Delivery Time Or Lead Time: 15-30days
- Q620E Extra Service:Pretreatment (Shot Blasting, Sand Blast, Painting and Galvanized), Cutting Parts, Sample Service, Third Party inspection, UT Test and Size inspection.
If you have any requirement in steel plate for Q620E, whether the new plate or stock list of material, please feel free to contact us by email of calling.
What is the key difference between Q620E and Q620D, and how to choose between them for project applications?
The core difference lies in low-temperature impact toughness requirements. Q620E must pass a Charpy V-notch impact test at -40℃ with minimum impact energy of 47J, while Q620D is tested at -20℃. For selection: Choose Q620E for projects in extremely cold regions (e.g., Northeast China, Qinghai-Tibet Plateau, polar mining sites) where temperatures drop below -30℃ for extended periods. Choose Q620D for temperate or mild cold areas (e.g., North China plains) to balance performance and cost-effectiveness.
Is Q620E easy to weld? What precautions should be taken during welding?
Q620E has good weldability thanks to its low carbon equivalent (≤0.45%), but strict precautions are needed to preserve its ultra-low-temperature toughness:
Use ultra-low-hydrogen welding consumables (diffusible hydrogen ≤5ml/100g) to avoid hydrogen-induced cold cracks.
Preheat plates ≥50mm thick to 100–120℃ before welding; maintain interpass temperature above 80℃ for multi-pass welding.
For critical components (e.g., offshore platform jackets), perform post-weld stress relief annealing at 200–250℃ to eliminate residual stress.
Avoid excessive heat input during welding, which may coarsen grains in the heat-affected zone and reduce low-temperature toughness.
What are the key process control points for cold forming Q620E into complex components?
Cold forming of Q620E requires strict control to prevent work hardening and hidden cracks:
Limit the single-pass cold deformation rate to ≤10%; adopt multi-pass forming with intermediate annealing (550–600℃) for complex shapes like crane boom sections.
Ensure the bending radius is no less than 3 times the plate thickness to avoid edge cracking.
Do not perform cold forming in environments below 0℃. If processing in cold workshops is unavoidable, preheat the steel to 30–50℃ first.
Conduct non-destructive testing (e.g., magnetic particle inspection) after forming to detect surface or subsurface cracks.