Steel structure manufacturer since 2009 · 8 fabrication bases in China
“Equivalent” grades have similar minimum yield strength. They are not identical: chemistry, impact testing, thickness limits and tolerances differ. Any substitution needs the engineer of record’s approval.
| China (GB/T 1591, 700) | Min. yield (≤16 mm) | USA (ASTM) | Europe (EN 10025) | Australia (AS/NZS) |
|---|---|---|---|---|
| Q235B | 235 MPa | A36 (250 MPa) | S235JR | 250 |
| Q355B | 355 MPa | A572 Gr50 / A992 (345 MPa) | S355JR | 350 |
| Q390 | 390 MPa | A572 Gr55 (380 MPa) | — | — |
| Q420 | 420 MPa | A572 Gr60 (415 MPa) | S420 | — |
| Q460 | 460 MPa | A572 Gr65 (450 MPa) | S460 | 450 |
Approximate comparison for planning. Check thickness-dependent yield values in each standard.
| Charpy test temperature | GB suffix | EN suffix |
|---|---|---|
| +20 °C | B | JR |
| 0 °C | C | J0 |
| −20 °C | D | J2 |
| −40 °C | E | K2 / NL |
Q345GJ and Q420GJ (GB/T 19879) are plates for building structures with tighter yield ranges, lower yield-to-tensile ratios and through-thickness options. Zengcheng New World used Q420GJC.
Substitution rule: propose, document and get written approval before ordering. Never substitute silently.
Send drawings or a brief. An engineer replies within 1 working day.
EN 1090-1 and EN 1090-2 for steel structures: execution classes EXC1–EXC4, factory production control, CE marking and supplier checks.
ISO 3834 parts 2, 3 and 4 for welding quality management, how they relate to EN 1090, and what to ask a fabricator.
AS/NZS 5131 for fabrication and erection of structural steel in Australia and New Zealand: construction categories CC1–CC4 and supplier requirements.