Carbon & Alloy Round Bar (Q235B, 20#, 45#, 20CrMnTi)
Solid hot-rolled round bar supplied in carbon, quality-carbon and alloy grades from Q195 to 42CrMo, in diameters from 6 mm to 300 mm with 6 m, 9 m and 12 m standard lengths. Stock is held in Shandong and dispatched to port within 3 days; cut-to-length and small trial quantities from one ton are welcome.
Product Overview
Round bar — also called black bar, carbon round bar or solid round steel — is the base material behind almost every fabricated metal part. It is produced by hot rolling, which leaves the original mill scale on the surface, so it offers the lowest cost per kilogram of any solid steel product and machines, welds, bends and drills without difficulty.
We supply three families from stock: plain carbon structural bar (Q195, Q215, Q235) for structures and general fabrication; quality carbon bar (10#, 20#, 35#, 45#) for shafts, bolts and machined parts; and alloy bar (20Cr, 40Cr, 20CrMo, 35CrMo, 42CrMo, 40CrNiMo, 20CrMnTi, GCr15, 65Mn) for gears, axles, bearings and moulds. Stainless 304 and 316 round bar is available for wet or corrosive indoor service.
Every heat is supplied with a mill test certificate showing chemical composition and mechanical properties, so the material can be verified against your drawing or against an incoming-inspection specification before it is cut.
Specifications & Size Range
Standard stock diameters and delivery lengths. Intermediate sizes and non-standard lengths are produced to order; cut-to-length (zero-cut) service is available on request and reduces offcut waste on machined parts.
| Diameter range | Common stock sizes (mm) | Standard length | Typical use |
|---|---|---|---|
| Small bar | 6, 8, 10, 12, 14, 16, 18, 20 | 6 m / 9 m / 12 m, coil for small sizes | Stirrups, bolts, hardware, agricultural frames |
| Medium bar | 22, 25, 28, 30, 32, 36, 40, 45, 50 | 6 m / 9 m | Shafts, pins, connecting parts, machine bases |
| Large bar | 55, 60, 65, 70, 80, 90, 100, 120, 150 – 300 | 6 m / 9 m, cut to order | Heavy shafts, moulds, press columns, ring blanks |
Tolerances
Diameter tolerance follows GB/T 702 (hot-rolled round bar): typically ±0.3 mm for small sizes and ±1.0% for larger sizes. Straightness and length tolerance confirmed on the mill certificate. Cold-drawn bar (h11 / h9) is available when tighter dimensional control is needed.
Steel Grades & International Equivalents
All grades below are supplied with a mill test certificate. The right-hand column shows the material type and the Chinese standard the grade is produced to; the middle columns give the nearest recognised equivalent in other national standards. Exact equivalence for a specific project should be confirmed on the enquiry.
| GB (China) | ASTM / AISI (US) | EN (Europe) | JIS (Japan) | DIN (Germany) | Type / Standard |
|---|---|---|---|---|---|
| Q195 | A36 (approx.) | S185 (EN 10025-2) | SS330 (JIS G3101) | St33 | Carbon structural steel (GB/T 700) |
| Q235B | A36 / A283 Gr.C | S235JR (EN 10025-2) | SS400 (JIS G3101) | St37-2 | Carbon structural steel (GB/T 700) |
| 20# (20 carbon steel) | AISI 1020 / ASTM A29 1020 | C22 (EN 10083) | S20C (JIS G4051) | CK22 | Quality carbon structural steel (GB/T 699) |
| 45# (45 carbon steel) | AISI 1045 / ASTM A29 1045 | C45 (EN 10083) | S45C (JIS G4051) | CK45 | Quality carbon structural steel (GB/T 699) |
| 20CrMnTi | AISI 8620 (approx.) | 20MnCr5 (EN 10084) | SCr420 (JIS G4104) | 20MnCr5 | Alloy carburizing steel (GB/T 3077) |
| 06Cr19Ni10 (304) | A240 TP304 / A276 304 | 1.4301 / X5CrNi18-10 | SUS304 (JIS G4304) | 1.4301 | Austenitic stainless steel (GB/T 3280 / GB/T 4237) |
| 022Cr17Ni12Mo2 (316L) | A240 TP316L | 1.4404 / X2CrNiMo17-12-2 | SUS316L (JIS G4304) | 1.4404 | Austenitic stainless steel (Mo-bearing) (GB/T 3280 / GB/T 4237) |
Grade Notes
- Q195 — Soft, highly formable. Standard grade for welded pipes, light sections and general fabrication.
- Q235B — The workhorse structural grade in China. Fully weldable, excellent cost-performance, the closest Chinese equivalent to ASTM A36 / EN S235JR.
- 20# (20 carbon steel) — Low-carbon quality steel with good weldability and cold formability. Standard material for seamless pipes, boilers and machined parts.
- 45# (45 carbon steel) — Medium-carbon steel for shafts, gears and axles. Responds well to quenching and tempering.
- 20CrMnTi — Case-hardening alloy steel: tough core with hard wear-resistant surface. Used for gears, shafts and transmission parts.
- 06Cr19Ni10 (304) — General-purpose austenitic stainless steel: corrosion resistant, formable and weldable. Non-magnetic in annealed condition.
- 022Cr17Ni12Mo2 (316L) — Mo-bearing stainless steel with superior resistance to chlorides and acids. Preferred for marine, chemical and food-grade equipment.
Chemical Composition (%, ladle analysis)
Typical specification limits. Actual heat values are reported on the mill test certificate supplied with every shipment.
| Grade | C | Si | Mn | P max | S max | Other elements |
|---|---|---|---|---|---|---|
| Q195 | ≤0.12 | ≤0.30 | 0.25–0.50 | ≤0.035 | ≤0.040 | — |
| Q235B | ≤0.20 | ≤0.35 | ≤1.40 | ≤0.045 | ≤0.045 | — |
| 20# (20 carbon steel) | 0.17–0.24 | 0.17–0.37 | 0.35–0.65 | ≤0.035 | ≤0.035 | — |
| 45# (45 carbon steel) | 0.42–0.50 | 0.17–0.37 | 0.50–0.80 | ≤0.035 | ≤0.035 | — |
| 20CrMnTi | 0.17–0.23 | 0.17–0.37 | 0.80–1.10 | ≤0.035 | ≤0.035 | Cr 1.00–1.30 Ti 0.04–0.10 |
| 06Cr19Ni10 (304) | ≤0.07 | ≤0.75 | ≤2.00 | ≤0.045 | ≤0.030 | Cr 18.0–20.0 Ni 8.0–10.5 |
| 022Cr17Ni12Mo2 (316L) | ≤0.030 | ≤0.75 | ≤2.00 | ≤0.045 | ≤0.030 | Cr 16.0–18.0 Ni 10.0–14.0 Mo 2.00–3.00 |
Mechanical Properties
Minimum values at room temperature unless stated. ReL = yield strength; Rp0.2 = 0.2% proof stress; Rm = tensile strength; A = elongation after fracture.
| Grade | Yield (ReL) | Proof (Rp0.2) | Tensile (Rm) | Elongation A | Impact / others | |
|---|---|---|---|---|---|---|
| Q195 | ≥195 MPa | — | 315–430 MPa | ≥33% | — | — |
| Q235B | ≥235 MPa | — | 370–500 MPa | ≥26% | +20 °C, ≥27 J | — |
| 20# (20 carbon steel) | ≥245 MPa | — | ≥410 MPa | ≥25% | — | — |
| 45# (45 carbon steel) | ≥355 MPa | — | ≥600 MPa | ≥16% | — | — |
| 20CrMnTi | ≥835 MPa (quenched & tempered) | — | ≥1080 MPa | ≥10% | — | — |
| 06Cr19Ni10 (304) | — | ≥205 MPa | ≥515 MPa | ≥40% | — | — |
| 022Cr17Ni12Mo2 (316L) | — | ≥170 MPa | ≥485 MPa | ≥40% | — | — |
Standards & Documents
- GB/T 702 — hot-rolled round and square steel bars (dimensions, shape, tolerance)
- GB/T 700 — carbon structural steels (Q195 / Q215 / Q235)
- GB/T 699 — quality carbon structural steels (10# / 20# / 35# / 45#)
- GB/T 3077 — alloy structural steels (20Cr / 40Cr / 42CrMo / 20CrMnTi)
- GB/T 1220 / GB/T 3280 — stainless steel bar (304 / 316L)
- EN 10204 3.1 mill test certificate with every shipment; SGS or BV third-party inspection on request
Typical Applications
| Industry / Application | Typical use |
|---|---|
| Construction & structural frames | Columns, bracing, base plates, embedded parts, guard-rail frames, anchor and tie rods. Bar for structural use is normally painted or galvanized after fabrication. |
| Machined shafts & transmission parts | Motor shafts, pump shafts, spindles, axles and connecting rods — 45# for general shafts, 40Cr and 42CrMo for high-load or wear-resistant shafts. |
| Gears, cams & carburized parts | 20CrMnTi gives a hard, wear-resistant case with a tough core, the standard choice for automotive and machinery gears. |
| Fasteners & hardware | Bolts, nuts, studs, anchors, turnbuckles and general hardware blanks. |
| Agricultural & mining machinery | Plough frames, harvester parts, crusher hammers and conveyor components where toughness under impact matters. |
| Bearings, springs & tooling | GCr15 bearing steel, 65Mn and 50Mn spring steel, and 3Cr2W8V / 5CrMnMo hot-work mould bar. |
| Fabrication & repair workshops | General machining stock, jigs and fixtures, brackets and small welded assemblies. |
Common Problems Buyers Face — and How We Prevent Them
These are the issues that most often cause claims on steel imports. Each one is controlled in our process before shipment.
Surface rust appearing before the parts are machined
Why it happens: Hot-rolled black bar has no protective coating, and humid sea air during a long transit will start surface oxidation within days.
Our control: Bar for sea freight is shipped dry and covered, with VCI paper and desiccant in the bundle on request. For rust-critical parts we supply pickled, oiled or cold-drawn bar, or hot-dip galvanized round bar.
Diameter running undersize, so the finished part is scrapped
Why it happens: Cheap bar can be rolled to the minus side of tolerance or even below the standard, and the loss is only discovered at the lathe.
Our control: We buy mill-certified bar only and confirm the diameter tolerance range in writing before shipment. Negative-tolerance stock is never shipped as standard material, and we can supply cold-drawn bar to h11 where the drawing demands it.
Hardness too high, so the bar will not machine cleanly
Why it happens: Quality-carbon and alloy bar can arrive in a hard as-rolled or incompletely annealed condition.
Our control: State the machining process on the enquiry. We supply 45# and alloy bar in annealed or normalized condition with hardness limits stated on the certificate (for example ≤229 HBW for 45#) so the tool life and cycle time you planned are actually achieved.
Cracking at the bend, or a weld that fails
Why it happens: Material of the wrong carbon or carbon-equivalent level has been selected for a cold-forming or welding operation.
Our control: We match the grade to the process — low-carbon Q195 / Q235 for bending and welding, medium-carbon and alloy grades for parts that will be machined and heat-treated instead. If your drawing specifies a grade you cannot source, send it to us and we will propose a documented equivalent.
Mixed material in one bundle
Why it happens: Several grades look identical in black mill condition, so picking errors happen at the mill or the yard.
Our control: Every bundle is tagged by heat number and grade and shipped with the matching mill certificate. Heat-number traceability is retained through loading so an identification check at your receiving bay takes minutes, not days.
Our Supply & Manufacturing Advantages
- One supplier, three material families — Plain carbon, quality carbon and alloy bar from a single order, so you are not combining several mills and several certificates on one shipment.
- Real stock, not a promise — Common diameters are held in our Shandong warehouse and dispatched to port within 3 days. Stock-only orders can be as small as one ton.
- Cut-to-length service — We cut to your part length before packing, which cuts offcut waste and freight weight on machined components.
- Documented material — EN 10204 3.1 mill test certificate with composition and mechanical properties for every heat, plus third-party inspection on request.
- Grade-matching support — Tell us the drawing requirement or the equivalent grade you normally buy (AISI 1045, AISI 8620, C45, S45C) and we will nominate the Chinese grade and confirm the equivalence in writing.
- Export packaging built in — Bundled with steel straps for container loading, or loose in bulk vessel for large tonnage, with rust protection where the route demands it.
Packaging, Delivery & Payment
- Packing: loose in bulk vessel, or bundled and containerised to your requirement. Galvanized and coated products get VCI paper, waterproof wrapping and edge protection. See our export packaging methods.
- Availability: both stock and custom production. Tell us the specification and we will confirm the route.
- MOQ: no strict minimum — one ton can ship.
- Lead time: stock dispatched to port within 3 days; orders needing export packaging about 1 week; custom production quoted per product.
- Payment: stock — 10% deposit, balance before shipment; custom production — 50% deposit, balance before shipment.
- Documents: EN 10204 3.1 mill test certificate with every shipment; third-party inspection (SGS / BV) on request.
Frequently Asked Questions
What is the Chinese equivalent of AISI 1045 round bar?
AISI 1045 corresponds to Chinese grade 45# (GB/T 699). The two are close on carbon and manganese content and on tensile strength, and 45# is normally supplied in the annealed condition for machining. If your drawing calls out AISI 1045 with a hardness limit, send us the limit and we will confirm that the 45# we ship will meet it.
What is the equivalent of AISI 8620 for carburized gears?
20CrMnTi (GB/T 3077) is the closest widely available Chinese equivalent, and 20CrMo is also used for the same duty. Both give a hard carburized case with a tough core. Because the alloying elements differ from 8620, we recommend confirming case depth and core hardness requirements on the enquiry.
Which grade should I choose for a machined shaft?
For general-purpose shafts use 45# bar. For high-load, fatigue-loaded or wear-resistant shafts use 40Cr or 42CrMo. For a hard surface with a shock-resistant core, for example a gear shaft, use 20CrMnTi and carburize.
Do you have a minimum order quantity?
No. We do not impose a strict minimum order quantity and can ship as little as one ton, which makes trial orders and small maintenance jobs practical.
Can you supply rounded, peeled or cold-drawn bar?
Yes. Cold-drawn (cold-finished) round bar is available in diameters up to about 80 mm to h11 / h9 tolerances with a bright, scale-free finish when your process needs tight dimensional control or a clean surface.
How do you prevent rust during sea transport?
Bundles are strapped and shipped dry, with VCI paper and desiccant where the route is long or humid. For parts that must arrive rust-free we supply pickled-and-oiled or cold-drawn bar, or hot-dip galvanized round bar with a coating of 30–700 g/m².
What documents come with a round bar shipment?
An EN 10204 3.1 mill test certificate showing heat number, chemical composition and mechanical properties, plus the commercial invoice, packing list and certificate of origin. Inspection by SGS or BV can be arranged before loading.
What is the lead time for round bar?
Stock diameters are dispatched to the port within 3 days. Orders that require export packaging or cutting to length take about one week to reach the port. Custom or non-standard sizes are quoted per product.
Can you source a grade that is not on your stock list?
In most cases yes. We buy from several steel mills and can source low-alloy, bearing, spring and mould grades including GCr15, 65Mn, 50Mn, 50Cr, 3Cr2W8V and 5CrMnMo. Send the specification and the quantity and we will confirm availability and lead time.
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