Grades · Q345B
Q345B Low-Alloy Structural Pipe
Low-alloy high-strength structural grade — the Chinese counterpart to S355. Where it becomes interesting is heat treatment: Q345B can be quenched and tempered up to Q420, Q460 and beyond, letting you buy one stocked grade and specify the strength you actually need.
133
Sizes in stock
Φ219–600
OD range (mm)
20–100
Wall range (mm)
GB/T 1591
Standard
International equivalents
| Chinese standard | GB/T 1591 · GB/T 8162 |
|---|---|
| Closest equivalent | EN S355JR |
| Also comparable | ASTM A572 Gr.50 |
| Also comparable | Now designated Q355B |
Typical properties
| Yield strength | ≥ 345 MPa (≤16mm section, standard minimum) |
|---|---|
| Tensile strength | 470–630 MPa |
| Impact | Grade B: 20 °C; C/D/E grades to −20 °C / −40 °C |
| Upgradeable to | Q390 · Q420 · Q460 · Q500 · Q550 · Q620 by Q&T |
Typical applications
- Structural steelwork and load-bearing frames
- Crane booms and lifting equipment
- Bridge and offshore structural members
- Pressure-bearing structural components
Delivery conditions
The delivery condition changes the material more than most buyers expect. Tell us what the part has to do and we will recommend one.
Hot rolledNormalizedQuenched & tempered (strength upgrade)Low-temperature impact guaranteed per EN or ASTM
Q345B sizes on the ground
133 combinations, updated 2026-08-22. Quantities turn over daily — confirm availability when you inquire.
| OD × Wall (mm) | OD (in) |
|---|---|
| Φ219 × 50 | 8.62″ |
| Φ219 × 55 | 8.62″ |
| Φ219 × 65 | 8.62″ |
| Φ224 × 26 | 8.82″ |
| Φ232 × 32 | 9.13″ |
| Φ232 × 45 | 9.13″ |
| Φ232 × 50 | 9.13″ |
| Φ232 × 55 | 9.13″ |
| Φ232 × 60 | 9.13″ |
| Φ245 × 28 | 9.65″ |
| Φ245 × 30 | 9.65″ |
| Φ245 × 35 | 9.65″ |
| Φ245 × 38 | 9.65″ |
| Φ245 × 40 | 9.65″ |
| Φ245 × 42 | 9.65″ |
| Φ245 × 45 | 9.65″ |
| Φ245 × 50 | 9.65″ |
| Φ254 × 30 | 10.00″ |
| Φ254 × 32 | 10.00″ |
| Φ254 × 35 | 10.00″ |
| Φ254 × 38 | 10.00″ |
| Φ254 × 40 | 10.00″ |
| Φ254 × 42 | 10.00″ |
| Φ255 × 23 | 10.04″ |
| Φ255 × 24.5 | 10.04″ |
| Φ273 × 28 | 10.75″ |
| Φ273 × 40 | 10.75″ |
| Φ273 × 42 | 10.75″ |
| Φ273 × 45 | 10.75″ |
| Φ273 × 50 | 10.75″ |
| Φ285 × 40 | 11.22″ |
| Φ285 × 42 | 11.22″ |
| Φ285 × 45 | 11.22″ |
| Φ299 × 20 | 11.77″ |
| Φ299 × 22 | 11.77″ |
| Φ299 × 28 | 11.77″ |
| Φ299 × 30 | 11.77″ |
| Φ299 × 32 | 11.77″ |
| Φ299 × 35 | 11.77″ |
| Φ299 × 36 | 11.77″ |
| Φ299 × 38 | 11.77″ |
| Φ299 × 40 | 11.77″ |
| Φ299 × 45 | 11.77″ |
| Φ299 × 50 | 11.77″ |
| Φ299 × 55 | 11.77″ |
| Φ299 × 60 | 11.77″ |
| Φ306 × 65 | 12.05″ |
| Φ325 × 39 | 12.80″ |
| Φ340 × 20 | 13.39″ |
| Φ340 × 40 | 13.39″ |
| Φ356 × 30 | 14.02″ |
| Φ377 × 20 | 14.84″ |
| Φ377 × 22 | 14.84″ |
| Φ377 × 25 | 14.84″ |
| Φ377 × 26 | 14.84″ |
| Φ377 × 30 | 14.84″ |
| Φ377 × 35 | 14.84″ |
| Φ377 × 40 | 14.84″ |
| Φ377 × 42 | 14.84″ |
| Φ377 × 45 | 14.84″ |
| Φ377 × 55 | 14.84″ |
| Φ377 × 80 | 14.84″ |
| Φ377 × 100 | 14.84″ |
| Φ390 × 30 | 15.35″ |
| Φ390 × 35 | 15.35″ |
| Φ390 × 40 | 15.35″ |
| Φ390 × 45 | 15.35″ |
| Φ395 × 60 | 15.55″ |
| Φ395 × 70 | 15.55″ |
| Φ402 × 25 | 15.83″ |
| Φ402 × 30 | 15.83″ |
| Φ402 × 35 | 15.83″ |
| Φ402 × 45 | 15.83″ |
| Φ402 × 55 | 15.83″ |
| Φ402 × 65 | 15.83″ |
| Φ402 × 70 | 15.83″ |
| Φ406 × 20 | 15.98″ |
| Φ406 × 25 | 15.98″ |
| Φ406 × 29 | 15.98″ |
| Φ406 × 30 | 15.98″ |
| Φ406 × 35 | 15.98″ |
| Φ406 × 40 | 15.98″ |
| Φ406 × 50 | 15.98″ |
| Φ406 × 65 | 15.98″ |
| Φ419.1 × 45 | 16.50″ |
| Φ419.1 × 60 | 16.50″ |
| Φ419.1 × 80 | 16.50″ |
| Φ426 × 25 | 16.77″ |
| Φ426 × 30 | 16.77″ |
| Φ426 × 35 | 16.77″ |
| Φ426 × 40 | 16.77″ |
| Φ426 × 45 | 16.77″ |
| Φ426 × 50 | 16.77″ |
| Φ426 × 60 | 16.77″ |
| Φ430 × 70 | 16.93″ |
| Φ431 × 50 | 16.97″ |
| Φ431 × 60 | 16.97″ |
| Φ440 × 80 | 17.32″ |
| Φ445 × 50 | 17.52″ |
| Φ450 × 55 | 17.72″ |
| Φ450 × 56 | 17.72″ |
| Φ450 × 100 | 17.72″ |
| Φ457 × 25 | 17.99″ |
| Φ457 × 30 | 17.99″ |
| Φ457 × 35 | 17.99″ |
| Φ457 × 45 | 17.99″ |
| Φ457 × 50 | 17.99″ |
| Φ457 × 55 | 17.99″ |
| Φ457 × 70 | 17.99″ |
| Φ457 × 80 | 17.99″ |
| Φ457 × 95 | 17.99″ |
| Φ457 × 100 | 17.99″ |
| Φ470 × 30 | 18.50″ |
| Φ470 × 32 | 18.50″ |
| Φ470 × 33 | 18.50″ |
| Φ470 × 45 | 18.50″ |
| Φ480 × 35 | 18.90″ |
| Φ480 × 65 | 18.90″ |
| Φ480 × 75 | 18.90″ |
| Φ490 × 63.5 | 19.29″ |
| Φ490 × 70 | 19.29″ |
| Φ508 × 26 | 20.00″ |
| Φ515 × 42 | 20.28″ |
| Φ520 × 47 | 20.47″ |
| Φ530 × 50 | 20.87″ |
| Φ530 × 55 | 20.87″ |
| Φ530 × 70 | 20.87″ |
| Φ530 × 90 | 20.87″ |
| Φ558 × 60 | 21.97″ |
| Φ560 × 60 | 22.05″ |
| Φ560 × 70 | 22.05″ |
| Φ570 × 70 | 22.44″ |
| Φ600 × 42 | 23.62″ |
Q345B — common questions
- What is Q345B equivalent to?
- Q345B is closest to EN S355JR, ASTM A572 Gr.50, Now designated Q355B. These are the standard comparisons used for sourcing; the mill certificate supplied with each shipment carries the actual chemistry and mechanical values for the heat.
- What sizes of Q345B do you stock?
- We currently hold 133 size combinations of Q345B, from Φ219mm to Φ600mm outside diameter with wall thickness from 20mm to 100mm.
- Can you supply Q345B heat treated?
- Yes. We supply Q345B in these delivery conditions: Hot rolled, Normalized, Quenched & tempered (strength upgrade), Low-temperature impact guaranteed per EN or ASTM. Heat treatment is done in-house before shipment and process records with temperature curves ship with the goods.
- Can Q345B be cut to length before shipment?
- Yes. We saw-cut to fixed lengths with a typical tolerance of ±1–2mm and end squareness of ≤1mm/100mm, so the material can go straight onto your machine without a facing operation.
Need Q345B in a size that isn't listed?
Non-standard sizes are our specialty — and for repeat requirements we hold dedicated stock. Send your size list and we'll confirm within 24 hours.