Xi'an Dongmeng Group Co., Ltd. is one of the most reliable manufacturers and suppliers of Stainless Steel Flat Bar Stock Supplier in China, also supports customized service. With abundant experience, we warmly welcome you to wholesale cheap products in stock here and get free sample from our factory. For price consultation, contact us.
Stainless Steel Flat Bar Stock Manufacturer
Dongmeng Group manufactures and supplies stainless steel flat bar stock for machinery, structural frames, architectural components, food-processing equipment, marine hardware and drawing-based OEM fabrication.
Our flat bars are available as hot-rolled mill bars, cold-finished precision bars and plate-cut rectangular bars. Customers can specify the grade, manufacturing route, dimensions, edge condition, surface finish, tolerance and processing requirements.
What Is Stainless Steel Flat Bar?
Stainless steel flat bar is a solid rectangular product ordered by:
Width × Thickness × Length
For example:
50 × 10 × 6000 mm
Unlike round bar, flat bar does not have a diameter. Unlike rectangular tube, it has no internal hollow section.
Flat bar is commonly used to manufacture:
Brackets
Frames
Supports
Base plates
Machine components
Architectural trims
Reinforcement members
Fastening plates
Custom welded assemblies
ASTM A276/A276M-25 covers hot-finished and cold-finished stainless steel bars and shapes for general applications. ASTM A484/A484M-24b provides the associated general requirements for stainless steel bars, billets, shapes and forgings.
Common Grades: 201 / 304 / 304L / 316 / 316L / 321 / 410 / 430
Special Grades: 17-4PH / 2205 / 2507 / 904L / 440C
Primary Bar Standard: ASTM A276/A276M-25
General Requirements: ASTM A484/A484M-24b
Pressure-Vessel Bar Standard: ASTM A479/A479M-25, when specified
European Standard: EN 10088-3:2023
Japanese Standard: JIS G 4303:2021
Typical Thickness: 3–100 mm
Typical Width: 10–300 mm
Standard Lengths: 2 / 3 / 4 / 5.8 / 6 m
Supply Routes: Hot Rolled / Cold Drawn / Ground / Plate Cut
Surface Options: Pickled / Mill Finish / Ground / Polished / No.4 Brushed
Edge Options: Mill Edge / Square Edge / Rounded Edge / Deburred / Chamfered
Processing: Saw Cutting / Laser Cutting / Waterjet Cutting / Milling / Drilling / Bending / Welding
Documents: Mill Test Certificate / PMI Report / Dimensional Inspection Report
Final availability depends on the selected grade, manufacturing route, dimensions, tolerance and quantity.
Three Types of Stainless Steel Flat Bar
The term "flat bar" can refer to products made through different manufacturing routes. Buyers should identify the required route before ordering because the edge shape, tolerance, surface, residual stress and certification can differ.
Hot-Rolled Mill Flat Bar
Hot-rolled flat bar is produced directly to a rectangular section during rolling.
Typical characteristics include:
Rounded or naturally formed mill edges
Hot-rolled and pickled surface
Economical production for common dimensions
Good suitability for welded structures
Wider dimensional tolerance than cold-finished bar
Lower machining cost for non-appearance-critical components
It is commonly ordered according to ASTM A276/A276M together with ASTM A484/A484M.
Cold-Drawn or Cold-Finished Flat Bar
Cold-finished bar is further processed after hot rolling to improve dimensional accuracy and surface condition.
Typical benefits include:
Tighter width and thickness tolerance
Improved straightness
Smoother surface
More consistent rectangular geometry
Better suitability for precision machining
Reduced finishing allowance
Cold working may increase strength and hardness while reducing ductility. The final condition and mechanical-property requirements must be stated in the purchase order.
Plate-Cut Flat Bar
Plate-cut flat bar is produced by shearing, laser cutting, plasma cutting, sawing or waterjet cutting stainless steel plate.
It is useful for:
Wide rectangular sections
Thick bars
Small production quantities
Non-standard dimensions
Drawing-specific blanks
Rapid prototype fabrication
When the material is cut from stainless steel plate, its primary material certificate will normally reference ASTM A240/A240M rather than ASTM A276. ASTM A240/A240M-26 applies to stainless steel plate, sheet and strip for pressure-vessel and general applications.
The quotation and MTC should clearly state whether the product is:
True mill flat bar
Cold-finished flat bar
Slit flat bar
Plate-cut rectangular bar
Product Specifications
| Parameter | Available Specification |
| Product | Solid stainless steel rectangular flat bar |
| Common Grades | 201, 304, 304L, 316, 316L, 321, 410 and 430 |
| Special Grades | 17-4PH, 2205, 2507, 904L and 440C |
| Typical Thickness | 3–100 mm |
| Typical Width | 10–300 mm |
| Special Sections | Wider or thicker sections by plate-cut production |
| Standard Length | 2, 3, 4, 5.8 or 6 m |
| Custom Length | Saw-cut or machined fixed lengths |
| Manufacturing Route | Hot rolled, cold drawn, ground, slit or plate cut |
| Standard Condition | Annealed or grade-specific heat-treated condition |
| Surface | Hot rolled and pickled, mill, ground, brushed or polished |
| Edge | Mill, square, rounded, deburred or chamfered |
| Straightness | ASTM A484 or drawing-specific |
| Width and Thickness Tolerance | ASTM A484 or customer specification |
| Processing | Cutting, milling, drilling, bending, welding and assembly |
| Material Identification | Grade, heat number, dimensions and batch marking |
| Documentation | EN 10204 3.1 MTC and inspection report upon request |
The published range should represent confirmed production capability rather than every theoretical dimension permitted by a standard.
Applicable Standards
| Requirement | Recommended Standard |
| General Stainless Steel Bars and Shapes | ASTM A276/A276M-25 |
| General Bar Requirements and Tolerances | ASTM A484/A484M-24b |
| Pressure-Vessel and Boiler Bars | ASTM A479/A479M-25 |
| Plate-Cut Rectangular Bars | ASTM A240/A240M-26 |
| European Stainless Steel Bars | EN 10088-3:2023 |
| Japanese Hot-Worked Stainless Bars | JIS G 4303:2021 |
| Free-Machining Stainless Bars | ASTM A582/A582M-22, where applicable |
| Inspection Certificate | EN 10204 3.1 or 3.2 |
ASTM A479/A479M is intended for stainless steel bars and shapes used in boiler and pressure-vessel construction. It should only be specified when the project requires this application-specific standard.
EN 10088-3:2023 covers semi-finished products, bars, rods, wire, sections and bright products made from corrosion-resistant stainless steels for general purposes.
JIS G 4303:2021 remains active and specifically includes hot-worked round, square, hexagonal and flat stainless steel bars.
Available Stainless Steel Grades
| Grade | Main Characteristic | Typical Applications |
| 201 | Economical austenitic stainless steel | Dry indoor frames, furniture and decorative parts |
| 304 | General corrosion resistance and fabrication | Machinery, food equipment and architectural components |
| 304L | Lower carbon for welded assemblies | Frames, tanks, supports and fabricated structures |
| 316 | Molybdenum-alloyed corrosion resistance | Chemical and humid-environment components |
| 316L | Improved suitability for welded corrosive service | Marine, pharmaceutical and process equipment |
| 321 | Titanium-stabilized austenitic grade | Elevated-temperature welded components |
| 410 | Hardenable martensitic grade | Wear parts, brackets and mechanical components |
| 430 | Economical magnetic ferritic grade | Indoor structures and appliance components |
| 17-4PH | Precipitation-hardening stainless steel | High-strength shafts, supports and machined parts |
| 2205 | High-strength duplex stainless steel | Chemical, marine and structural applications |
| 2507 | Super duplex stainless steel | Aggressive chloride and offshore environments |
| 440C | High-carbon, high-hardness stainless steel | Wear-resistant tooling and precision parts |
Grade availability varies between hot-rolled, cold-finished and plate-cut production.
Duplex grades provide substantially higher strength than conventional annealed austenitic stainless steels and strong resistance to stress-corrosion cracking, but require controlled welding and heat treatment.
304 vs 316L Stainless Steel Flat Bar
| Selection Factor | 304 / 304L | 316 / 316L |
| General Corrosion Resistance | Good | Higher |
| Molybdenum Content | No intentional addition | Approximately 2–3% |
| Indoor Fabrication | Widely used | Suitable but often higher cost |
| Coastal and Chloride Exposure | Limited according to severity | Generally preferred |
| Welding | Good | Good |
| Typical Cost | Lower | Higher |
| Common Applications | Equipment, frames and architecture | Marine, chemical and pharmaceutical equipment |
Grade 304 is suitable for many general indoor, food-equipment and mild exterior applications. Grade 316L is generally considered where chloride exposure, humidity or process chemicals require increased localized-corrosion resistance.
Material selection must account for temperature, chloride concentration, cleaning chemicals, deposits, crevices and expected service life.
304 vs 304L and 316 vs 316L
The L grades have controlled lower carbon content.
Lower carbon helps reduce chromium-carbide precipitation in the heat-affected zones of welded components.
Choose an L grade when:
Extensive welding is required
Post-weld solution treatment is not practical
Resistance to intergranular corrosion is important
The project specification explicitly requires the low-carbon grade
Do not substitute 304 for 304L or 316 for 316L without checking the purchase specification and design requirements.
Surface and Edge Options
Hot-Rolled and Pickled
A matte industrial surface suitable for structures, supports and components that will be machined or fabricated.
Cold-Finished
A smoother surface with improved dimensional consistency for machined and appearance-sensitive components.
Ground
Grinding removes surface irregularities and can provide controlled thickness, width or roughness.
No.4 Brushed
A directional satin finish suitable for architectural trims, furniture and visible frames.
Polished
A brighter decorative surface for equipment, architectural and sanitary applications.
World Stainless describes No.4 as a general-purpose polished finish produced using approximately 120–150 mesh abrasives, while mirror finishes require progressively finer polishing and buffing.
Edge Options
Available edge treatments include:
Natural hot-rolled radius
Square mill edge
Sheared edge
Laser-cut edge
Waterjet-cut edge
Saw-cut edge
Deburred edge
Rounded edge
Chamfered edge
Fully machined edge
Appearance-critical components should be ordered with an approved surface and edge sample.
Dimensional Tolerance and Straightness
Do not publish one universal tolerance for every flat bar.
Permitted variation depends on:
Manufacturing route
Width
Thickness
Length
Stainless steel grade
Hot- or cold-finished condition
Edge type
Applicable dimensional standard
Additional machining
ASTM A484/A484M provides general requirements for stainless steel bars and shapes, including dimensional and manufacturing provisions. Where tighter tolerances are required, the purchase order should state the actual acceptable limits rather than only writing "precision tolerance."
Example purchasing requirement:
50.00 × 10.00 × 3000 mm
Width: +0.00 / −0.15 mm
Thickness: +0.00 / −0.10 mm
Straightness: maximum 1 mm per metre
Four edges deburred
The feasibility of these example tolerances must be confirmed before production.
Flat Bar Weight Calculation
The approximate theoretical weight can be calculated as:
Weight, kg/m = Width × Thickness × Density ÷ 1,000,000
For common austenitic stainless steel, an approximate density of 7,930 kg/m³ may be used for initial commercial calculations.
Example:
50 mm × 10 mm flat bar
Approximate weight:
50 × 10 × 7,930 ÷ 1,000,000 = 3.965 kg/m
The final invoiced weight may be based on actual weight or the agreed theoretical-weight method.
Stainless Steel Flat Bar Price
There is no single reliable price for every stainless steel flat bar.
The quotation depends on:
Grade
Nickel, molybdenum, chromium and other alloying elements affect the raw-material cost. Grades 316L, 2205, 2507 and 904L normally have different price structures from 304.
Manufacturing Route
Hot-rolled mill flat bar, cold-drawn flat bar and plate-cut bar require different production and finishing processes.
Dimensions
Very thin, narrow, wide or thick rectangular sections may require special tooling, plate cutting or additional machining.
Surface Finish
Hot-rolled and pickled material is generally less expensive than precision-ground, brushed or polished bar.
Tolerance
Tighter width, thickness, straightness, flatness and edge tolerances increase processing and inspection costs.
Quantity
Production setup, minimum rolling quantity and cutting loss affect the final price per kilogram or metre.
Additional Processing
Saw cutting, laser cutting, drilling, milling, bending, welding and assembly are quoted separately.
Inspection and Documentation
PMI, ultrasonic testing, mechanical testing, EN 10204 3.2 certification and third-party inspection can affect the price.
Packaging and Freight
Export cases, surface protection, destination charges and Incoterms should be included when comparing quotations.
A professional quotation should identify:
Material + Manufacturing Route + Processing + Inspection + Packaging + Freight
Custom OEM and ODM Processing
Dongmeng Group can supply full-length bar, cut blanks or finished components according to customer drawings.
Available services include:
Precision saw cutting
Laser cutting
Waterjet cutting
Milling
Surface grinding
Drilling
Tapping
Slot processing
Chamfering
Edge rounding
Bending
Welding
Surface brushing
Polishing
Component assembly
Custom part numbering
Export kits
For drawing-based production, provide:
CAD or PDF drawing
Grade and material standard
Dimensions and tolerances
Surface-finish requirement
Edge condition
Weld specification
Inspection requirement
Annual or batch quantity
Fabrication Recommendations
Cutting
Use clean tools and equipment dedicated to stainless steel to prevent contamination from carbon steel.
Machining
Austenitic stainless grades work harden during machining. Use rigid equipment, sharp tooling and stable feeds that remain below the hardened surface layer.
Bending
Bending force, springback and minimum radius depend on the grade, thickness, rolling direction and material condition.
Welding
Grades 304L and 316L are commonly selected for welded components. Duplex, martensitic and precipitation-hardening grades require grade-specific procedures.
Surface Restoration
Remove heat tint, embedded iron and grinding contamination after welding where corrosion performance is important. Suitable cleaning may include grinding, pickling or passivation.
Structural-Use Notice
ASTM A276 material compliance does not automatically establish the load capacity of a completed structure.
For safety-critical structural applications, the project engineer should specify:
Structural design code
Stainless steel grade
Product condition
Minimum mechanical properties
Section dimensions
Connection design
Welding procedure
Load combinations
Deflection limits
Corrosion environment
Inspection level
A plate-cut bar and a true mill bar with the same dimensions may have different edge geometry, residual stress and dimensional tolerances.
Typical Applications
Stainless steel flat bars are used for:
Machine frames
Equipment supports
Mounting brackets
Conveyor components
Commercial kitchen equipment
Food-processing machinery
Pharmaceutical equipment
Architectural trims
Railings and balustrades
Doors and window frames
Marine hardware
Chemical-processing equipment
Base plates
Connection plates
Grilles and screens
Furniture frames
Transportation equipment
Renewable-energy structures
Custom machined components
Welded OEM assemblies
Grade, size and production route should be selected according to the load, corrosion environment, fabrication process and required appearance.
Quality Inspection
Inspection can be arranged according to the material standard, purchase order and approved drawing.
Available controls include:
Grade and heat-number verification
Mill Test Certificate review
PMI testing
Width and thickness measurement
Length inspection
Straightness and flatness inspection
Edge and corner inspection
Surface-finish inspection
Hardness testing
Tensile testing when required
Ultrasonic testing for applicable heavy sections
Processed-part drawing inspection
Packaging and identification inspection
Available Documents
EN 10204 3.1 Mill Test Certificate
Certificate of Conformity
Chemical composition report
Mechanical test report
PMI report
Hardness report
Dimensional inspection report
Surface-roughness report
Ultrasonic test report
Third-party inspection report
Heat-number and packing list
Required testing and documentation must be agreed before production.
Packaging and Export Protection
Packaging options include:
Steel-strapped bundles
Waterproof wrapping
Plastic or foam separators
Protective film for polished surfaces
Wooden pallets
Fully enclosed wooden cases
Edge and corner protection
Grade and heat-number tags
Cut-part identification
Customer-specific shipping marks
Ground, brushed and polished bars should be separated to reduce friction scratches during transport.
Why Choose Dongmeng Group?
Dongmeng Group provides stainless steel raw-material supply, cutting, machining, surface finishing, inspection and international delivery support.
Customers can receive:
Hot-rolled and cold-finished flat bars
Plate-cut custom rectangular bars
Austenitic, ferritic, martensitic and duplex grades
Standard and drawing-specific dimensions
Custom edge and surface finishing
Saw, laser and waterjet cutting
OEM machining and welded assemblies
MTC and PMI documentation
Third-party inspection support
Custom export packaging
FOB, CFR, CIF and DDP delivery support
Request a Stainless Steel Flat Bar Quote
For an accurate quotation, please provide:
Stainless steel grade
Required material standard
True flat bar or plate-cut bar
Width
Thickness
Length
Quantity
Manufacturing route
Surface finish
Edge condition
Dimensional tolerance
Straightness requirement
Processing drawing
Inspection and certification requirements
Destination port or delivery address
Company: Dongmeng Group
Email: office@dongmjd.com
Phone / WhatsApp: +86 157 6921 4734
Frequently Asked Questions
How is stainless steel flat bar specified?
Flat bar is normally specified as width × thickness × length, for example 50 × 10 × 6000 mm.
Is flat bar measured by diameter?
No. Diameter is used for round bar. Stainless steel flat bar is measured by width and thickness.
Which ASTM standard applies to stainless steel flat bar?
ASTM A276/A276M is commonly used for general stainless steel bars and shapes, together with ASTM A484/A484M for general requirements and tolerances.
Is plate-cut flat bar covered by ASTM A276?
Not automatically. When a rectangular bar is cut from plate, the base material is generally certified to ASTM A240/A240M. The manufacturing route must be identified in the quotation and MTC.
What is the difference between hot-rolled and cold-drawn flat bar?
Hot-rolled bar is more economical and usually has a rougher surface and wider tolerance. Cold-drawn bar provides improved surface quality, straightness and dimensional accuracy.
Which grade is most common?
Grade 304 is the common general-purpose choice. Grade 316L is selected where increased resistance to chlorides, humidity or chemicals is required.
Can you supply polished flat bars?
Yes. Ground, brushed and polished finishes can be supplied. Specify the finished faces, grain direction, roughness and protective-film requirement.
Can flat bars be cut to fixed lengths?
Yes. Saw cutting, laser cutting, waterjet cutting and machined fixed-length components are available.
Can you produce bars from customer drawings?
Yes. Dongmeng Group can provide drilling, tapping, slots, milling, chamfering, bending, welding and component assembly.
Can flat bar be used as a pressure-retaining component?
Only after engineering review. ASTM A479/A479M may apply to bars used in boiler or pressure-vessel construction, but the completed component must comply with the governing design code.
Can you supply EN or JIS material?
Yes. EN 10088-3:2023 and JIS G 4303:2021 requirements can be reviewed when stated in the purchase order. These standards should not be treated as automatically identical to ASTM A276.
What information affects the price?
The main factors are grade, manufacturing route, dimensions, tolerance, surface, edge condition, processing, quantity, inspection, packaging and delivery terms.
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