Q235B is the most widely used ordinary carbon structural steel in China, defined by the national standard GB/T 700. When it is roll-formed into bearing bars and cross bars and welded or press-locked into panels, it becomes Q235B steel grating — the workhorse flooring material of industrial platforms, walkways, drainage covers and galvanized stair treads.
Values are ladle analysis per GB/T 700. The low carbon content (carbon equivalent typically 0.30–0.38) is what gives Q235B its excellent weldability — grating panels are resistance-welded at high speed without preheating or special consumables, and fabricated panels can be arc-welded to supports on site without cracking.
Grating bearing bars are typically 3–6 mm thick, i.e. inside the 235 MPa / 26% column. Values are guaranteed minimums — every heat is tested and recorded on the mill test certificate.In practice this means a grating panel made of Q235B can be designed with a certified 235 MPa yield point, deforms plastically instead of breaking when overloaded (elongation ≥ 26%), resists impact damage during handling and service (27 J at 20 °C), and can be cold-bent into serrated profiles or punched without edge cracking.
Hot-dip galvanizing is the standard finish: the finished panel is dipped in molten zinc, giving a typical coating of 65–85 µm on 3–6 mm sections (per GB/T 13912 / ISO 1461) and decades of maintenance-free outdoor life. For chemical or marine plants, stainless grating or a heavier duplex system can be specified instead.
All four grades sit at the 235–250 MPa yield level and are commonly accepted as substitutes for general structural use — Q235B grating is routinely exported to projects that specify S235JR or A36, with the equivalence documented on the mill certificate. The differences that do exist (impact guarantees, phosphorus/sulfur limits, certification systems) are compared in detail in our companion articles on ASTM A36 grating and Q235B vs S235JR.
They are near-equivalents: both guarantee a 235 MPa minimum yield strength, similar tensile range (Q235B 370–500 MPa, S235JR 360–510 MPa) and 27 J at +20 °C. S235JR has slightly stricter phosphorus and sulfur limits (≤ 0.035% vs ≤ 0.045%). For most grating applications they are interchangeable, subject to the project specification. 2. What is the difference between Q235A and Q235B grating?
Class A carries no impact test guarantee, while class B guarantees 27 J Charpy V-notch energy at +20 °C. Grating should be ordered in class B for any load-bearing or outdoor application; class A is suitable only for light, non-critical uses. 3. Can Q235B grating be certified to EN or ASTM standards?
The steel is supplied with a GB/T 700 mill test certificate in EN 10204 3.1 format stating the measured composition and properties. Most international buyers accept this as evidence of equivalence; for projects that formally require EN 10025 or ASTM material, dual-certified or alternative grades can be arranged at the mill. 4. What zinc coating does Q235B grating receive?
Standard hot-dip galvanizing to GB/T 13912 / ISO 1461 — typically 65–85 µm (about 460–600 g/m²) on 3–6 mm bearing bars, verified by coating-mass tests. Galvanizing is done after fabrication, so welds and cut edges are fully protected. 5. Do you supply test reports with grating shipments?
Yes. Every shipment includes the mill test certificate (chemistry and mechanical properties) and galvanizing records; third-party inspection (SGS, BV, TUV) can be arranged before loading.👉 Contact GNEE For Q235B Steel Grating With Full Mill Test Certificates.
What Does The Grade Name Q235B Mean?
The designation follows the Chinese naming system for carbon structural steels:- Q —the Chinese word for yield strength
- 235 — minimum yield strength, 235 MPa, for sections up to 16 mm thick
- B — quality class defined by impact testing: class A has no impact requirement; class B guarantees 27 J at +20 °C; class C at 0 °C; class D at −20 °C
Q235B Chemical Composition (GB/T 700, Heat Analysis, Max. %)
| Grade | C | Si | Mn | P | S |
|---|---|---|---|---|---|
| Q235B | ≤ 0.20 | ≤ 0.35 | ≤ 1.40 | ≤ 0.045 | ≤ 0.045 |
Q235B Mechanical Properties (GB/T 700)
| Property | ≤ 16 mm | 16–40 mm | 40–60 mm |
|---|---|---|---|
| Yield strength, min. (MPa) | 235 | 225 | 215 |
| Tensile strength (MPa) | 370 – 500 | 370 – 500 | 370 – 500 |
| Elongation A, min. (%) | 26 | 26 | 25 |
| Charpy V-notch impact (longitudinal) | 27 J min. at +20 °C (class B) | ||
| 180° bend test | No crack, mandrel diameter = 1.5 × thickness | ||
The Standards Stack For Q235B Steel Grating
A grating order actually touches four different standards. Knowing the full stack helps you specify correctly and avoid disputes:| Level | Chinese Standard | International Counterpart | What It Covers |
|---|---|---|---|
| Base material | GB/T 700 | EN 10025-2 / ASTM A36 / JIS G3101 | Chemical composition and mechanical properties of the steel |
| Product standard | YB/T 4001.1 | NAAMM/MBG 531 (US), BS 4592 (UK) | Grating dimensions, tolerances, load requirements, marking |
| Corrosion protection | GB/T 13912 | ISO 1461 / ASTM A123 | Hot-dip galvanized coating mass and uniformity |
| Inspection documents | GB/T 17505 | EN 10204 type 3.1 | Mill test certificate issued with each shipment |
International Equivalents Of Q235B
| China (GB/T 700) | Europe (EN 10025-2) | USA (ASTM) | Japan (JIS G3101) |
|---|---|---|---|
| Q235B | S235JR (1.0038) | ASTM A36 | SS400 |
All four grades sit at the 235–250 MPa yield level and are commonly accepted as substitutes for general structural use — Q235B grating is routinely exported to projects that specify S235JR or A36, with the equivalence documented on the mill certificate. The differences that do exist (impact guarantees, phosphorus/sulfur limits, certification systems) are compared in detail in our companion articles on ASTM A36 grating and Q235B vs S235JR.
Why Q235B Is The Default Grating Steel
- Certified structural strength — a guaranteed 235 MPa yield point lets engineers run load calculations, not guesswork (see our load capacity guide).
- Outstanding weldability — low carbon and low carbon equivalent allow high-speed resistance welding of every cross bar without preheat.
- Guaranteed toughness — the 27 J / 20 °C impact requirement of class B covers normal outdoor service temperatures.
- Universal availability and cost — Q235B flat bars are produced by every Chinese mill, keeping grating prices low and lead times short.
- Proven export track record — accepted as the practical equivalent of S235JR and A36 on projects worldwide.
FAQ
1. Is Q235B the same as S235JR?They are near-equivalents: both guarantee a 235 MPa minimum yield strength, similar tensile range (Q235B 370–500 MPa, S235JR 360–510 MPa) and 27 J at +20 °C. S235JR has slightly stricter phosphorus and sulfur limits (≤ 0.035% vs ≤ 0.045%). For most grating applications they are interchangeable, subject to the project specification. 2. What is the difference between Q235A and Q235B grating?
Class A carries no impact test guarantee, while class B guarantees 27 J Charpy V-notch energy at +20 °C. Grating should be ordered in class B for any load-bearing or outdoor application; class A is suitable only for light, non-critical uses. 3. Can Q235B grating be certified to EN or ASTM standards?
The steel is supplied with a GB/T 700 mill test certificate in EN 10204 3.1 format stating the measured composition and properties. Most international buyers accept this as evidence of equivalence; for projects that formally require EN 10025 or ASTM material, dual-certified or alternative grades can be arranged at the mill. 4. What zinc coating does Q235B grating receive?
Standard hot-dip galvanizing to GB/T 13912 / ISO 1461 — typically 65–85 µm (about 460–600 g/m²) on 3–6 mm bearing bars, verified by coating-mass tests. Galvanizing is done after fabrication, so welds and cut edges are fully protected. 5. Do you supply test reports with grating shipments?
Yes. Every shipment includes the mill test certificate (chemistry and mechanical properties) and galvanizing records; third-party inspection (SGS, BV, TUV) can be arranged before loading.👉 Contact GNEE For Q235B Steel Grating With Full Mill Test Certificates.
