ASTM A514 Grade B and Q690E are both high-strength, quenched & tempered (Q&T) alloy steels for heavy structures, but A514 Gr B is an American standard (ASTM) with ~690 MPa yield strength, while Q690E is a Chinese standard (GB/T) offering comparable strength and excellent low-temperature toughness, often used for bridges, cranes, and heavy machinery where high strength and impact resistance are crucial. The key difference lies in their governing standards and specific alloy compositions (like chromium/molybdenum for toughness), though they serve similar high-performance applications.
Chemical Composition of A514 GR B
|
|
|
|
|---|---|---|
|
0.12-0.21 |
0.10-0.23 |
|
|
0.70-1.00 |
0.66-1.04 |
|
|
0.035 max |
0.043 max |
|
|
0.035 max |
0.043 max |
|
|
0.40-0.80 |
0.35-0.85 |
|
|
0.40-0.65 |
0.35-0.70 |
|
|
0.15-0.30 |
0.12-0.33 |
|
|
0.03-0.08 |
0.01-0.10 |
|
|
0.0005-0.005 |
0.0000-0.0055 |
Chemical Composition of Q690E
|
|
C |
P |
S |
B |
V |
|||||||||
|
Q690E |
0.2 |
0.8 |
1.7 |
0.020 |
0.010 |
0.5 |
1.5 |
2 |
0.7 |
0.005 |
0.12 |
0.06 |
0.0 |
|
Mechanical Properties of A514 GR B
|
Elongation (min, % in 2") |
Charpy V-Notch Impact (min, ft-lb at -20℃F) |
||||
|---|---|---|---|---|---|
|
Up to 2.5 |
100 / 690 |
110-130 / 760-895 |
18 |
235-293 |
20 (supplemental) |
|
2.5 to 6 |
90 / 620 |
100-130 / 690-895 |
16 |
235-293 |
20 (supplemental) |
Q690E
|
Q690E |
|||||||||||
|
50 |
50-100 |
100-150 |
50 |
50-100 |
100-150 |
% |
0 |
-20 |
-40 |
-60 |
|
|
690 |
650 |
630 |
770-940 |
710-900 |
14 |
|
|
37 |
|
||
ASTM A514 Grade B
Type: Quenched & Tempered Alloy Steel Plate.
Strength: Minimum yield strength of 100 ksi (690 MPa).
Properties: High strength, good formability, and toughness, often with optional Charpy V-notch impact testing.
Uses: Heavy machinery, construction equipment, crane booms, truck frames, bridges, and mobile lifts.
Q690E (GB/T 16270)
Type: Chinese high-strength, fine-grain structural steel (Q&T).
Strength: Minimum yield strength of 690 MPa.
Properties: Excellent low-temperature toughness (often tested to -40℃ or lower), good weldability, fine-grain structure.
Uses: Similar high-stress applications as A514, including heavy-duty machinery, bridges, and offshore structures, especially in cold climates.
Strength Level: They are functionally equivalent in terms of their 690 MPa minimum yield strength.
Toughness: Q690E often emphasizes superior low-temperature impact toughness due to its specific alloying, making it ideal for extreme cold.
Standards: A514 is ASTM (US), while Q690E is GB/T (China).
Application: Both are top choices for heavy, weight-sensitive structures requiring high load capacity and resistance to impact, like cranes and large equipment.
