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Carbon Steel Bar

Carbon Steel Bar Supplier

Carbon steel round, flat, square and hex bars supplied for structural fabrication, machining and general manufacturing, with hot-rolled and cold-finished routes, cut lengths, inspection, traceability and export packing available.

ShapesRound · Flat · Square · Hex
Structural GradesA36 · A572 Gr.50 · Q355 · S355
Machining Grades1018 · 1020 · 1045 · C45 · S45C
DeliveryMill length · Cut length · Oiled where required
Carbon steel bar stock and supply
Bar Shapes

Round, Flat, Square or Hex?

Start with the cross-section shown on the drawing. The shape changes how the bar is measured, processed and inspected, so we do not treat every steel bar as the same product.

Round Bar

Common for shafts, pins, machined components and general fabrication.

Order by diameter × length.

Flat Bar

Used for brackets, straps, supports, fabricated parts and general manufacturing.

Order by thickness × width × length.

Square Bar

Used in structural fabrication, general components and machining blanks.

Order by side × side × length.

Hex Bar

Used for machined components, fittings and parts where a hexagonal section reduces later machining.

Order by across-flats size × length.
Carbon steel round flat square and hex bars
Round bar is not rebar.

Smooth carbon steel round bar is supplied for fabrication or machining. Reinforcing bar has a ribbed profile and is ordered to concrete-reinforcement standards. For ribbed reinforcement, see Steel Rebar →

Grades by Use

Choose the Grade from What the Bar Has to Do

A bar that will be welded into a frame is bought differently from a bar that will be turned into a shaft. We separate structural grades from machining grades so the quotation follows the actual use.

Structural / General Fabrication

For Welding, Frames and Fabricated Parts

ASTM A36ASTM A572 Grade 50Q235Q355S235S355SS400

These grades are commonly selected where strength, weldability and fabrication are more important than later turning or precision machining.

Machining / Engineering Bar

For Shafts, Pins and Machined Components

SAE 1018SAE 1020SAE 104520#45#C45S20CS45C

For machining-bar orders, carbon level, finished diameter, straightness, surface and machining allowance can matter more than a structural-strength designation.

Cold-finished or hot-rolled bar standards such as ASTM A108 or A576 are reviewed when they match the requested supply route.
A36 and 1045 are not interchangeable by default.

A36 is usually purchased as a structural grade. 1045 is a medium-carbon engineering grade commonly selected when machining, hardness or mechanical performance matters more. Tell us what the finished part does, not just the dimensions.

Buying Route

Structural Bar or Machining Bar?

The same bar shape can follow two very different buying routes. A structural bar is usually selected around grade, section and weldability. A machining bar is selected around the finished component as well.

01

Structural Work

Start with grade, bar shape, section size, length and fabrication requirement.

02

Machined Components

Add finished diameter, machining allowance, straightness and required surface condition.

03

If You Only Have a Drawing

Send the drawing. We can review whether the material callout matches a structural or machining-bar route.

Carbon steel bar grade and application review
Surface & Dimensional Route

Hot-Rolled or Cold-Finished Bar?

The choice is not only about appearance. It changes surface condition, dimensional control and how much machining may be needed later.

01

Hot-Rolled Bar

Common for structural work and machining blanks where a mill-scale surface and broader dimensional tolerance are acceptable.

02

Cold-Finished Bar

Chosen when a cleaner surface and closer size control reduce later machining or finishing work.

03

Temporary Rust Protection

Oiling can be reviewed when storage or shipment conditions require additional short-term protection.

Hot rolled and cold finished carbon steel bars
How to Specify Size

Give the Dimension That Matches the Bar Shape

A clear size description prevents quotation errors. We confirm the available mill size after the grade and quantity are known.

Bar ShapeHow to Specify ItExample RFQ Format
Round BarDiameter × LengthØ50 mm × 6,000 mm
Flat BarThickness × Width × Length10 × 100 × 6,000 mm
Square BarSide × Side × Length50 × 50 × 6,000 mm
Hex BarAcross Flats × LengthAF 36 mm × 6,000 mm
Need cut blanks instead of mill lengths?

Send the finished blank length and whether the piece will be machined later. We can review whether extra stock should remain for facing, turning or other subsequent machining.

Inspection by Shape

Different Bar Shapes Need Different Measurements

A round bar is not checked the same way as a square, flat or hex bar. The inspection points follow the geometry that matters to the next operation.

Carbon steel round bar diameter and straightness inspection
Round Bar

Diameter & Straightness

Diameter is measured at suitable positions and straightness is checked when it affects machining or assembly.

Carbon steel square and hex bar dimensional inspection
Square / Hex

Side, Diagonal & Across Flats

Square bar is checked by side and diagonal; hex bar is checked across flats, together with straightness or twist where required.

Carbon steel flat bar thickness width and edge inspection
Flat Bar

Thickness, Width & Edge

Thickness, width, straightness and edge condition are checked against the confirmed supply route.

Cut Length & Allowance

Cut the Bar for the Next Operation

Mill lengths are not always the most efficient form for a machine shop or fabrication line. Bars can be cut into shorter blanks when that reduces handling or later sawing work.

01

Saw Cutting

Suitable bars can be cut to fixed blank lengths before packing.

02

Machining Allowance

If the cut blank will be faced or turned, include the finished part size so suitable allowance can be reviewed.

03

Cut-End Check

Finished blank length and cut-end condition can be checked before bundling or boxing.

Carbon steel bar cut to length processing
Traceability

Cut Pieces Still Need to Match the Original Material

Cutting a six-meter bar into shorter blanks should not remove the link to the original heat and material certificate. Identification is carried through processing and packing when traceability is required.

01Mill / heat number
02Original bar and MTC
03Cutting record
04Short blank identification
05Bundle / box tag
06Shipment documents
Carbon steel bar MTC and cut piece traceability
Packing & Shipment

Long Bars and Short Blanks Need Different Packing

Packing is based on length, section, surface condition and handling risk rather than using the same bundle for every bar order.

01

Long Bars

Bundled with multiple steel straps and supported at several points to reduce bending and handling damage.

02

Short Cut Blanks

Pallets or boxes can be used when short pieces would be unsafe or difficult to handle as a conventional long bundle.

03

Cleaner / Finished Surfaces

Additional rust and surface protection can be used when the delivered surface needs more protection than standard hot-rolled bar.

Carbon steel bar export packing
Related Products

Other Bar and Structural Material Options

Ordering Questions

Common Questions Before Quotation

What is the difference between A36 and 1045 steel bar?

A36 is commonly selected for structural fabrication and welding. 1045 is a medium-carbon engineering steel commonly selected for machined or mechanical components where carbon level and mechanical performance matter more. They should not be substituted automatically.

Should I buy hot-rolled or cold-finished bar?

Use the required surface, dimensional tolerance and next operation as the guide. Hot-rolled bar is common for structural work and machining blanks; cold-finished bar is useful when closer size control or a cleaner surface reduces later work.

Can bars be cut to fixed lengths?

Yes, for suitable orders. Send the required blank length and tell us whether the piece will be machined afterward so machining allowance can be considered.

What size information should I send?

For round bar send diameter × length; flat bar thickness × width × length; square bar side × side × length; and hex bar across-flats size × length.

Request a Quote

Send Your Carbon Steel Bar Requirement

Grade, bar shape, size, length, quantity and destination are enough to start. If the bars will be machined later, add the finished-part requirement or upload the drawing.

Thank you. Your requirement has been received.
PDF, Word, Excel or image. Maximum 10 MB.