Bridge Structural Plate
Grades with a q were born for bridges. Bridges carry dynamic loads and stand in the weather for a century, so the steel is held to a stricter line than general structural plate: higher impact requirements, fatigue-ready toughness, and through-thickness (Z) properties on heavy sections to prevent lamellar tearing. In GB/T714, the letter after q — C, D, E — sets the impact temperature.
| Grade | Thickness mm | Impact temp. | Standard |
|---|---|---|---|
| Q345qC | 8–120 | 0°C | GB/T714 |
| Q345qD | 8–120 | -20°C | GB/T714 |
| Q345qE | 8–120 | -40°C | GB/T714 |
| Q370qC / D / E | 8–120 | 0°C to -40°C | GB/T714 |
| Q420qC / D / E | 8–110 | 0°C to -40°C | GB/T714 |
| Q460qD / E | 8–100 | -20°C / -40°C | GB/T714 |
Typical applications
Ordering notes
Bridge plate is usually specified line-by-line by the design documents: Z grade (Z15/Z25/Z35), UT class, through-thickness reduction of area, sometimes atmospheric-corrosion requirements or weathering bridge grades (Q345qDNH and friends). Every added clause touches melting and inspection — get them all into the contract.
Delivery discipline matches: we file mill certificates by heat number, check stencil and UT report plate by plate, and support witness sampling by the supervisor. Wuyang, Xianggang and Angang bridge plate carries references on mainline railways and river crossings — booking and inspection routines we know by heart.
常见问答
What does q stand for?
It is the initial of the Chinese word for bridge. Q420qD reads as 420 MPa yield bridge steel impact-tested at -20°C, with tighter toughness and fatigue requirements than ordinary Q420D.
Is Z grade mandatory?
Where welded joints pull through the plate thickness — box-girder webs to flanges, node plates — lamellar tearing is the risk, and designs typically demand Z15 upward, Z25/Z35 for critical nodes. The drawings decide; we verify reduction-of-area values on the certificate.
Can bridge plate be weathering?
Yes. GB/T714 includes corrosion-resistant bridge grades (NH suffix, e.g. Q345qDNH) for uncoated or heavily protected service — sea crossings often choose them, with slightly longer lead times.
Further reading
A few related pieces worth a look: