Carbon Steel Round Bar Manufacturer

Carbon Steel Round Bar

Dual supply: hot‑rolled black bar & precision cold‑drawn bright bar for different machining demands
Wide size coverage: hot rolled Φ10‑300mm; cold drawn precision Φ3‑80mm
Ultra‑tight tolerance for cold‑drawn bar: ±0.02‑0.05 mm, less secondary machining work
Flexible service: standard 6m/12m lengths, support custom cut‑to‑length & zero‑cut

Product Overview

Carbon Steel Round Bar is a solid cylindrical carbon steel product widely used for mechanical processing, forging and structural fabrication. It is available in two main forms: hot-rolled black surface round bar and cold-drawn bright precision round bar, providing different solutions for rough machining, structural applications and precision component manufacturing.

Manufactured and inspected according to international standards including GB/T702, GB/T905, ASTM A675, ASTM A108, EN10060 and EN10278, our carbon steel round bar covers multiple steel grades including Q235B, Q355B, 20#, 45#, 1018 and 1045 to meet different mechanical and fabrication requirements.

The hot-rolled carbon steel round bar is available in diameters from Φ10mm to Φ300mm, suitable for general machining, forging blanks and structural components. The cold-drawn bright round bar provides higher dimensional accuracy with diameter ranges from Φ3mm to Φ80mm and tolerance as low as ±0.02-0.05mm, reducing additional machining workload.

With standard lengths of 6m and 12m, plus custom cut-to-length service, Carbon Steel Round Bar can be supplied according to different component sizes and production requirements. It is widely applied in shaft parts, gear blanks, forging components, agricultural machinery parts, engineering machinery components and steel structure connections.

Carbon Steel Round Bar

Chemical & Mechanical Property Snapshot

Grade	Standard	C (%)	Mn (%)	Si (%)	S (%) ≤	P (%) ≤	Yield Strength (MPa)	Tensile Strength (MPa)	Elongation (%)
Q235B	GB/T 702	0.12–0.22	0.30–0.70	≤0.35	0.045	0.045	≥235	370–500	≥26
Q355B	GB/T 702	≤0.20	1.00–1.60	≤0.50	0.035	0.035	≥355	470–630	≥21
20#	GB/T 702 / GB/T 905	0.17–0.23	0.35–0.65	0.17–0.37	0.035	0.035	≥245	≥410	≥25
45#	GB/T 702 / GB/T 905	0.42–0.50	0.50–0.80	0.17–0.37	0.035	0.035	≥355	≥600	≥16
1018	ASTM A108	0.14–0.20	0.60–0.90	≤0.25	0.050	0.040	≥250	440–560	≥25
1045	ASTM A108	0.42–0.50	0.60–0.90	≤0.25	0.050	0.040	≥310	585–740	≥16

Detailed Technical Specifications

Item	Specification
Product Name	Carbon Steel Round Bar
Material Type	Carbon Steel
Product Shape	Solid Round Bar
Surface Type	Hot-rolled black surface / Cold-drawn bright surface
Manufacturing Standards	GB/T702, GB/T905, ASTM A675, ASTM A108, EN10060, EN10278
Hot Rolled Grades	Q235B, Q355B, 20#, 45#
Hot Rolled Diameter Range	Φ10mm-Φ300mm
Common Hot Rolled Sizes	Φ12, Φ14, Φ16, Φ18, Φ20, Φ25, Φ30, Φ40, Φ50, Φ60, Φ80, Φ100, Φ120, Φ150, Φ200, Φ250, Φ300mm
Cold Drawn Grades	1018, 1045, 20#, 45#
Cold Drawn Diameter Range	Φ3mm-Φ80mm
Cold Drawn Tolerance	±0.02-0.05mm
Standard Length	6m / 12m
Cutting Service	Custom cut-to-length and zero-cut service
Quality Documentation	Mill Test Certificate including heat identification, chemical composition and mechanical properties
Packaging	Steel strapped bundles for seaworthy export transportation
MOQ	5 Ton
Payment Terms	T/T, L/C at Sight
Delivery Time	7–15 working days after receiving deposit

Size Specification Table

Type	Diameter Range	Common Available Diameters	Standard Length	Tolerance	Cutting Service
Hot Rolled Round Bar	Φ10 mm–Φ300 mm	Φ12, Φ14, Φ16, Φ18, Φ20, Φ25, Φ30, Φ40, Φ50, Φ60, Φ80, Φ100, Φ120, Φ150, Φ200, Φ250, Φ300	6 m / 12 m	Standard hot-rolling tolerance	Custom cut-to-length & zero-cut
Cold Drawn Bright Round Bar	Φ3 mm–Φ80 mm	Φ3, Φ4, Φ5, Φ6, Φ8, Φ10, Φ12, Φ14, Φ16, Φ20, Φ25, Φ30, Φ40, Φ50, Φ60, Φ70, Φ80	6 m / 12 m	±0.02–0.05 mm	Custom cut-to-length & zero-cut

Product Comparison Table

Comparison Item	Hot-Rolled Carbon Steel Round Bar	Cold-Drawn Carbon Steel Round Bar
Surface Condition	Black surface with mill scale	Smooth, bright precision surface
Available Grades	Q235B, Q355B, 20#, 45#	1018, 1045, 20#, 45#
Equivalent International Grade	Q235B ≈ S235JR; Q355B ≈ S355JR; 20# ≈ 1020; 45# ≈ 1045	1018 ≈ Q235B; 1045 ≈ 45#; 20# ≈ 1020; 45# ≈ 1045
Manufacturing Standard	GB/T 702, ASTM A675, EN 10060	GB/T 905, ASTM A108, EN 10278
Diameter Range	Φ10 mm–Φ300 mm	Φ3 mm–Φ80 mm
Dimensional Tolerance	Standard hot-rolling industrial tolerance	Ultra-tight tolerance ±0.02–0.05 mm
Processing Characteristics	Suitable for rough machining, forging blanks, and structural fabrication	Suitable for precision machining and finished components; reduces secondary machining
Typical Applications	Forging blanks, shafts, structural parts, machinery components, foundation bolt blanks	Precision shafts, mechanical pins, turned & milled components, gear blanks
Recommended Selection	Select for large-diameter, general structural, and rough-machining projects	Select for high-precision requirements, less material removal, and tight dimensional control

App Market

Reliable Steel Coil Solutions For Diverse Industrial Applications

Mechanical Shaft Components

Gear Blanks

Agricultural Machinery Parts

Product Packaging

Secure Export Packaging For Safe Handling And Delivery

FAQs

What is Carbon Steel Round Bar used for?

Carbon Steel Round Bar is widely used for shaft parts, gear blanks, forging blanks, machinery components, anchor bolt blanks and steel structure connections.

What standards does Carbon Steel Round Bar comply with?

The product complies with GB/T702, GB/T905, ASTM A675, ASTM A108, EN10060 and EN10278 standards.

What is the difference between hot-rolled and cold-drawn Carbon Steel Round Bar?

Hot-rolled round bar is suitable for general machining and forging, while cold-drawn round bar provides brighter surface finish and tighter tolerance for precision machining.

What sizes of Carbon Steel Round Bar are available?

Hot-rolled round bar is available from Φ10mm to Φ300mm, while cold-drawn round bar covers Φ3mm to Φ80mm.

Can Carbon Steel Round Bar be cut according to customer requirements?

Yes. Standard lengths are 6m and 12m, and custom cut-to-length and zero-cut services are available.

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Carbon Steel Round Bar Manufacturer