Q235 carbon steel round bar is the most widely stocked general-purpose bar grade exported from China, equivalent in role to JIS SS400, ASTM A36 and EN S235JR. Supplied hot rolled or cold drawn in diameters from 6 mm to 400 mm, it combines a guaranteed 235 MPa yield strength with excellent weldability and forming behavior, making it the default choice for frames, fasteners, machine parts and construction hardware. Huaxia-Steel supplies Q235 round bar directly from audited Chinese mills with EN 10204 3.1 certificates and export-grade packing.
Product Overview
Governed by GB/T 700 (technical delivery conditions) and GB/T 702 (hot rolled bar dimensions), Q235 is a plain low-carbon steel with carbon typically 0.14–0.20%. The “235” in the name is the minimum yield strength in MPa measured on 16 mm thickness. Q235 subdivides into quality levels A, B, C and D; Q235B (20 °C impact test) is the export default, while Q235C/D offer impact testing at 0 °C and −20 °C for colder service. Because the grade welds freely with CEV typically 0.28–0.36, fabricators use it without preheat in sections under 25 mm.
Dimensions and Tolerances
| Parameter | Range | Standard tolerance |
|---|---|---|
| Diameter (hot rolled) | 6–100 mm | GB/T 702 class 1 (±0.4 to ±0.9 mm by size) |
| Diameter (large bar) | 100–400 mm | GB/T 702 / forged bar tolerances by agreement |
| Cold drawn / bright | 3–80 mm | h9–h11 available |
| Length | 5.8 m / 6 m / 12 m | +50/0 mm standard; fixed length on request |
| Straightness | — | ≤ 0.4% of length (0.2% for bright bar) |
| Weight tolerance | — | ±4% per bundle (GB/T 702) |
Chemical Composition and Mechanical Properties
| Element | Q235B limit |
|---|---|
| C | ≤ 0.20% |
| Si | ≤ 0.35% |
| Mn | ≤ 1.40% |
| P | ≤ 0.045% |
| S | ≤ 0.045% |
| Property | Value (≤ 16 mm) |
|---|---|
| Yield strength | ≥ 235 MPa |
| Tensile strength | 370–500 MPa |
| Elongation | ≥ 26% |
| Impact test (Q235B) | ≥ 27 J at 20 °C |
| Hardness | ~120–140 HB as rolled |
International Grade Equivalents
| China GB | Japan JIS | USA ASTM | Europe EN | Germany DIN |
|---|---|---|---|---|
| Q235B | SS400 | A36 (dual-certifiable) | S235JR (1.0038) | St 37-2 (historic) |
Mills can issue dual certificates (Q235B/SS400 or Q235B/A36) after confirming the destination standard’s supplementary requirements — always request the equivalence table on the MTC when your end client audits documents.
Manufacturing Standards and Process
- GB/T 700-2006 — carbon structural steels, chemistry and mechanical requirements.
- GB/T 702-2017 — dimensions, shape, weight and tolerances of hot rolled bars.
- GB/T 2101 — general requirements for acceptance, packaging and marking.
- Process: EAF or BOF melting → continuous casting → hot rolling (roughing/intermediate/finishing) → cooling → straightening → bundling; optional cold drawing or peeling for bright bar.
Typical Applications
Q235 round bar is used for building reinforcement hardware, anchor and foundation bolts, machine frames and brackets, drive shafts for light duty, pins and spacers, grate bars and fencing components, furniture tubes and general fabrication stock. Its free-machining behavior is adequate for moderate production volumes; for high-volume turning, 1018/12L14-type grades reduce tooling cost.
Quality Assurance
- EN 10204 3.1 mill test certificate with ladle analysis, tensile and impact results for every heat.
- Spectral analysis verification and dimension checks before packing; report issued per shipment.
- Optional third-party inspection (SGS, BV, TUV, Intertek) at the mill before shipment.
- Optional UT testing for diameters above 80 mm on request.
- Low-temperature grades Q235C/D available with 0 °C / −20 °C impact testing.
Packing and Shipping
Bars are bundled at 1–2 tonnes with steel strapping, ends protected, and each bundle stenciled with grade, size, heat number and bundle weight. Seaworthy packing options include woven bag or hessian wrap, plastic caps on machined ends, and container (20/40 ft) or breakbulk loading. Container bundles are limited to 5.8 m for 20 ft units; 12 m lengths ship via 40 ft open top or breakbulk. Typical delivery: 7–15 days for stock sizes, 20–35 days for production orders of 20–500 tonnes.
Q235 Quality Levels: A, B, C and D
The grade letter defines impact testing requirements and, implicitly, the cleanliness of the steel:
| Level | Impact test | Typical use |
|---|---|---|
| Q235A | None required | Non-critical hardware, fencing, furniture |
| Q235B | 20 °C, ≥ 27 J | Export default, general structures |
| Q235C | 0 °C, ≥ 27 J | Outdoor structures in temperate climates |
| Q235D | −20 °C, ≥ 27 J | Cold-region service, tighter S/P (≤ 0.035%) |
Theoretical Weight per Metre (Common Sizes)
| Diameter | Weight (kg/m) | 12 m bar (kg) |
|---|---|---|
| 12 mm | 0.888 | 10.7 |
| 16 mm | 1.58 | 19.0 |
| 20 mm | 2.47 | 29.6 |
| 25 mm | 3.85 | 46.2 |
| 32 mm | 6.31 | 75.8 |
| 50 mm | 15.42 | 185 |
| 80 mm | 39.46 | 473 |
| 100 mm | 61.65 | 740 |
Use these figures for freight estimation (weight basis, not piece count) and for reconciling mill invoices against your theoretical calculation — a standard practice in steel trade audits.
Surface and Processing Options
- Hot rolled (as-rolled): mill scale surface, cheapest, ready for welding and secondary fabrication.
- Peeled / turned: scale-free smooth surface for machining feed; diameter tolerance to h11.
- Cold drawn bright: tight tolerance (h9 available), higher yield via work hardening, best for CNC.
- Galvanized: hot dip after fabrication for outdoor hardware.
- Cut-to-length and chamfering: delivered ready for your production line on request.
Frequently Asked Questions
Is Q235B round bar acceptable where A36 is specified?
For most non-code applications yes, with dual certification on the MTC. For ASME or building-code work, confirm with the engineer of record; many accept dual-certified material, some require actual A36 melt practice.
What is the largest diameter you can supply?
Hot rolled rounds run to 400 mm from section mills and forging plants; above 200 mm, forged and rough-machined bar with UT testing is the standard route and is quoted on request.
Can you cut and machine to my drawing?
Yes — cut-to-length, chamfering, drilling, turning and welding services are available in-house or via partner shops, with the finished parts packed per your assembly sequence.
Machining, Welding and Fabrication Notes
Q235 machines acceptably with standard high-speed steel or carbide tooling at moderate speeds; cutting speeds around 25–35 m/min with HSS and 120–180 m/min with carbide are typical, and sulfur dioxide-free cutting fluids extend tool life. Welding needs no preheat below 25 mm and no post-weld treatment for most joints — CEV sits near 0.30. Bending is comfortable at 1.5t inside radius for bars and plates under 12 mm; for larger radii or heavy cold work, order Q235C/D for extra toughness.
Common downstream services we arrange: sawing to length, chamfering, centering, rough turning, drilling and threading, plus bending and welding into sub-assemblies. Finished parts can be packed in the sequence your assembly line needs — a small detail that saves hours of sorting on the receiving dock.
Export Ordering Checklist
- Grade and quality level (Q235B default, C/D for low temperature).
- Diameter and tolerance class (hot rolled class 1, or cold drawn h9–h11).
- Length (5.8 m / 6 m / 12 m or fixed cut) and quantity in tonnes or pieces.
- Standard reference (GB/T 700 + GB/T 702) plus any dual-certification requirement.
- Surface condition, packing type and marking/labelling language.
- Certificate type (EN 10204 3.1) and optional third-party inspection.
- Incoterm and destination port.
An RFQ with these seven lines receives a firm, comparable quotation within one working day — and eliminates the back-and-forth that usually delays first orders by a week.
Corrosion Protection and Storage
As an uncoated plain carbon steel, Q235 relies on temporary protection. Mill-supplied oil film lasts roughly 3–6 months indoors; hot dip galvanizing to ISO 1461 (55–85 μm) extends service life outdoors to 20–30 years in rural atmospheres and 10–15 years in industrial or coastal air. Painted systems (epoxy zinc-rich primer plus polyurethane topcoat) are common for exposed structural hardware. Whatever you choose, storage matters: keep bundles under cover, off the ground, with air circulation, and never wrap cold-drawn bar tightly in plastic — trapped condensation rusts bright bar faster than open air does.
Where Q235 Round Bar Sells Best
Export demand concentrates in four markets: Middle East construction hardware and fence posts, African infrastructure and general fabrication, South American machinery and agricultural implements, and South Asian fastener and hardware production. In each of these markets the buying decision is driven less by grade nuance and more by three things — certificate completeness, packing that survives the voyage, and price stability over rolling quarterly orders. Our export team maintains stock positions in the common diameters (12–100 mm) so repeat orders can ship within two weeks without re-pricing the whole mill schedule.
Why Buy Q235 Round Bar Factory Direct
Trading companies add a layer between you and the mill — and with it, a margin, a delay and a gap in traceability. Buying direct through Huaxia-Steel means the heat numbers on your certificates trace to a named mill, inspection can be witnessed at source, and production slots can be reserved against your rolling schedule rather than whatever stock happens to be available. For buyers running 2–4 container loads per quarter, the combination of mill pricing, reserved capacity and single-point documentation typically saves 4–8% against spot trader quotations while improving certificate quality.
Every shipment leaves with the full document pack: EN 10204 3.1 certificates, packing list with heat and bundle mapping, dimensional inspection record and, where requested, third-party inspection reports. That is the difference between a delivery you can audit and one you have to trust.
Weight and Quantity Reconciliation
Steel is invoiced by weight, and the reconciliation between theoretical and actual weight is where disputes start. GB/T 702 permits a ±4% bundle weight tolerance, so a 25-tonne order can legitimately invoice 24 tonnes; asking for the weighbridge certificate plus the theoretical calculation on the packing list makes the difference visible and auditable. For cold drawn bright bar, tolerance is tighter and invoicing often follows piece count times theoretical weight — state your preferred basis in the PO so there is no ambiguity when the invoice arrives.
Request a Quote for Q235 Round Bar
Send your diameter, length, quantity and destination port to the Huaxia-Steel sales team — we reply with mill-direct pricing, current stock availability and CIF/CFR/FOB options within 24 hours. Custom lengths, cold drawn sizes and dual-certified MTCs are all supported from our partner mills.
