GB/T is China's national (national-recommended) standard system. The structural steel buyer's map: GB/T 700 (carbon steels — Q235B), GB/T 1591 (high-strength low-alloy — Q355B), GB/T 11263 (H beams HW/HM/HN), GB/T 706 (channels & angles), GB/T 3091 (galvanized welded pipe), GB/T 8162 (seamless structural pipe). GB grades map directly to EN/ASTM/JIS: Q235B ≈ S235JR ≈ A36 ≈ SS400; Q355B ≈ S355JR ≈ A572 Gr50 — Chinese mills roll GB by default, so it is the fastest and cheapest supply route.
When you buy steel from China, the mill's native language is GB — the Chinese national standard system. Mills roll GB grades by default at their best prices and shortest lead times; EN and ASTM designations are usually special runs. Understanding the GB system is therefore the key to cheaper steel — and to the equivalence certificates that make GB material importable almost everywhere.
The GB/T Standards Every Buyer Meets
| Standard | Covers | You Order |
|---|---|---|
| GB/T 700 | Carbon structural steels | Q195, Q215, Q235B, Q275 — tubes, angles, channels, light sections |
| GB/T 1591 | High-strength low-alloy steels | Q355B/C/D (ex-Q345) — beams, columns, plates |
| GB/T 11263 | Hot-rolled H sections | HW/HM/HN series — the GB H beam system |
| GB/T 706 | Channels & angles | Channels 5#–40a/c; equal angles 2.5#–20# |
| GB/T 3091 | Welded steel pipe (incl. galvanized) | DN15–DN200 Q235B pipe — fencing, water, structure |
| GB/T 8162 / 8163 | Seamless pipes (structural / fluid) | 20#, 45# steel seamless tubes |
| GB/T 3274 / 912 | Hot-rolled plates & sheets | Q235B, Q355B plate 2–200 mm |
What "Q235B" Actually Says
- Q =屈服强度 qufu (yield strength) — the number after it is the minimum yield in MPa.
- 235 = 235 MPa minimum yield (the S235/A36 class).
- B = impact quality class: B tested at +20 °C (27 J), C at 0 °C, D at −20 °C, E at −40 °C.
- So "Q355D" reads: 355 MPa yield, impact-tested at −20 °C — exactly the S355J2/A572-class envelope.
GB Grades → EN / ASTM / JIS Equivalents
| GB Grade | EN | ASTM | JIS | Notes for Substitution |
|---|---|---|---|---|
| Q235B | S235JR | A36 | SS400 | Direct structural substitute in most non-code work — see the full trio comparison |
| Q355B | S355JR | A572 Gr50 | SM490 | The workhorse HSLA grade — Q355B deep dive |
| Q355C/D | S355J0/J2 | A572 + CVN | SM490C | Cold-climate impact classes |
| 20# steel | C22E / 1.1151 | 1020 | S20C | Seamless tube base |
Full cross-standard charts: GB equivalents · stainless equivalents · S355JR vs Q355B detail
Which Overseas Markets Build with GB Material
- Southeast Asia — Vietnam, Philippines, Indonesia, Malaysia, Cambodia: Chinese-standard sections and pipes dominate private construction and factory builds.
- Africa — Nigeria, Kenya, Ghana, Tanzania: Chinese EPC projects and local fabricators buy GB sections and GI pipe routinely.
- Middle East & Latin America — private industrial works accept GB with equivalence documentation.
- Belt & Road EPC projects — designed to GB from the drawing stage.
Where codes lock EN/ASTM grades (public works, pressure equipment), the fix is equivalence documentation: mill certificates naming GB grades plus the mapping to the required standard, reviewed by the project engineer. We supply the certificates; the engineer signs.
How to Order GB Material (and Save)
- Send your sizes — in GB designations (HW 250×250, 20a channel, DN100 pipe) or your home standard; we map either way.
- Choose the quality suffix (B/C/D) by service temperature — most tropical projects take B.
- Get mill certificates 3.1 naming the GB standard plus our equivalence statement for your records.
- Ship FOB Foshan/Guangzhou or CIF — container math here.
GB product pages: GB H beam (HW/HM/HN) · GB pipe (GB/T 3091 & 8162) · Q235B plate · GB weight tables (46 H sizes)
GB prices are the mill's best prices — ask for them
Size list to [email protected] or WhatsApp +86 191 5745 8011 — GB material quoted with equivalence documentation in one working day. MOQ 5 t.
Request GB Steel Quote