Steel Flat Bar

Steel Flat Bar

Steel flat bar is a versatile, cost-effective steel product used across construction, manufacturing, and fabrication industries. Defined by its rectangular shape, flat bar offers consistent strength, easy machinability, and broad availability in standard sizes and grades. Steel Supply stocks steel flat bar in a wide range of thicknesses, widths, and lengths to meet the demands of both structural and precision applications.

Whether you’re building frames, fabricating brackets, machining components, or reinforcing structural assemblies, steel flat bar provides a reliable solution with predictable performance.

Available Sizes

Steel flat bar is available in many standard sizes and can be supplied cut-to-length to reduce waste and processing time.

Thickness

Common thicknesses include:

• 1/8"

• 3/16"

• 1/4"

• 3/8"

• 1/2"

• 3/4"

• 1"

Heavier thicknesses are available by request depending on grade and mill availability.

Width

Standard widths typically range from:

• 1/2" up to 12"

Length

• Standard mill lengths: 20 feet

• Custom cut lengths available to meet job-specific requirements

Dimensional tolerances vary based on whether the flat bar is hot rolled or cold finished.

Grades and Specifications

Steel Supply offers steel flat bar in common carbon steel grades as well as specialty grades for higher-performance applications.

ASTM A36

• Most widely used structural steel grade

• Minimum yield strength of 36 ksi

• Excellent weldability and formability

• Ideal for construction, base plates, brackets, and general fabrication

• Supplied primarily as hot rolled flat bar

AISI 1018 (Cold Finished)

• Low-carbon steel with good machinability

• Smooth surface finish and tighter tolerances

• Commonly used for machined parts, frames, and precision components

• Available as cold rolled or cold drawn flat bar

Additional Grades

Depending on availability, flat bar can also be sourced in:

• Alloy steels such as 4140

• Specialty grades for strength, wear resistance, or corrosion resistance

Manufacturing Process

Steel Flat Bar can be manufactured by two different methods – rolling at the Steel Mill which produces Mill Flats or Sheared and Edged from steel plate. Flats that are sheared and edged have a different finish on the edge from the flat sides and are not as precisely dimensioned.

1/8” carbon steel flats are sheared and edged, 3/16” & 1/4” carbon steel flats are routinely produced by both methods, and most others are mill flats.Steel flat bar is produced using either hot rolling, cold finishing, or slit from  each process delivering specific advantages.

Hot Rolled Flat Bar - Mill Flats

Hot rolled flat bar is manufactured by heating steel slabs or billets to high temperatures and passing them through rolling mills to achieve the desired thickness and width. After rolling, the steel is air-cooled, resulting in a durable product with mill scale on the surface.

Advantages of hot rolled flat bar:

• Cost-effective

• Excellent for welding and fabrication

• Ideal for structural and industrial applications

• Widely available in larger sizes

Cold Finished Flat Bar

Cold finished flat bar starts as hot rolled steel and undergoes additional processing such as pickling and cold rolling or drawing. This process improves surface finish and dimensional accuracy while increasing strength.

Advantages of cold finished flat bar:

• Tighter tolerances

• Smoother surface finish

• Improved machinability

• Ideal for precision parts and machining applications

Applications

Steel flat bar is commonly used in:

• Structural supports and bracing

• Frames and base plates

• Brackets and gussets

• Agricultural and industrial equipment

• Trailer and truck fabrication

• Machinery and machined components

• Ornamental and architectural steelwork

Its simple geometry and wide size availability make flat bar easy to cut, drill, weld, and machine.

Why Buy Steel Flat Bar from Steel Supply

• Broad inventory of sizes and grades

• Cut-to-length services available

• Reliable sourcing and consistent quality

• Knowledgeable sales support

• Fast turnaround for fabrication and construction needs

Steel Supply provides steel flat bar you can depend on — stocked, processed, and delivered to keep your project moving.