304 stainless steel flat bar is a rectangular solid flat structural section made of classic 18-8 austenitic stainless steel. It is manufactured by hot rolling, cold drawing, straightening, pickling and precision finishing, featuring flat smooth surfaces, uniform thickness, precise width tolerance and straight edges without burrs.

With balanced chromium and nickel composition, 304 flat bar combines excellent corrosion resistance, outstanding ductility, superior weldability and good machinability. It can be cut, drilled, bent, stamped, welded and machined freely, widely used as anti-rust supporting frames, brackets, base plates, decorative strips, mechanical fixture blanks and hardware raw materials for food, medical, construction, machinery, chemical and outdoor engineering. It is the most universal and cost-effective stainless flat steel for general anti-corrosion structural applications.

2. Global Equivalent Grade Cross Reference (All Mainstream Standards)

Note: Minor differences in element tolerance ranges among standards; all grades are fully interchangeable for ordinary industrial and decorative use, with no obvious difference in processing performance and service life.

3. Chemical Composition (wt%, ASTM / EN / GB Standard Limit)

Core Composition Advantages:
Low carbon content (C ≤0.08%: Effectively avoids chromium carbide precipitation during welding, prevents intergranular corrosion at weld seams.
18%–20% Chromium: Forms a dense self-repairing passive oxide film on the surface, providing stable rust and oxidation resistance in atmospheric, fresh water and mild acid & alkali environments.
8%–10.5% Nickel: Stabilizes complete austenite microstructure, delivers high toughness and fully non-magnetic property under annealed state.
Strict control of low sulfur & phosphorus: Eliminates cracking risks during cold bending, stamping and welding.

4. Physical & Mechanical Properties

4.1 Basic Physical Properties (Room Temperature, Solution Annealed State)

Density: 7.93 g/cm³
Melting range: 1398 ~ 1454 ℃
Thermal conductivity: 16.2 W/m·K
Specific heat capacity: 500 J/kg·K
Resistivity: 0.72 Ω·mm²/m
Linear thermal expansion coefficient (20–200℃): 17.2 × 10⁻⁶ /℃
Elastic Modulus E: 193 GPa
Shear Modulus G: 72 GPa
Poisson’s Ratio: 0.24
Magnetism: Completely non-magnetic after full annealing; slight weak magnetism generated after cold rolling, cutting or bending (normal physical phenomenon)

4.2 Mechanical Properties (Solution Annealed Flat Bar)

Performance Feature: Excellent plasticity and toughness, no fracture during heavy cold forming; cold drawn bright flat bar has higher tensile strength and hardness for precision machined parts.

5. Product Specifications & Surface Finishes

5.1 Size Range

Width: 10mm ~ 300mm
Thickness: 2mm ~ 30mm
Standard Length: 6000mm; custom cut-to-length service available
Dimensional Tolerance: Hot rolled black flat bar: ±0.3~±1.0mm Cold drawn bright flat bar: ±0.02~±0.05mm Precision calibrated flat bar: ±0.01~±0.03mm
Edge Condition: Rounded edge / sharp clean edge without burrs for selection

5.2 Common Surface Types

●Hot Rolled Black Surface Covered with black oxide scale, low cost, suitable for hidden structural supports without appearance requirements.
●Pickled Matte Silver Surface Oxide skin removed, uniform silver-gray finish, easy for welding, cutting and secondary machining (most widely exported grade).
●Cold Drawn Bright Surface Smooth metallic bright surface, tight dimensional tolerance, for precision mechanical blanks and visible decorative parts.
●Polished Mirror Surface High gloss mirror finish, anti-fouling, used for high-end decoration, sanitary equipment and visible hardware strips.

6. Core Key Features

Excellent General Corrosion Resistance Resist rust, oxidation, humidity, fresh water and mild acid-base media; suitable for long-term indoor and outdoor service. Not applicable for seawater and high chloride environment (choose 316L instead).

Superior Machinability & Formability High ductility supports cutting, drilling, tapping, bending, stamping without cracking; easy to process into various brackets and structural parts.

Outstanding Welding Performance Low carbon design avoids weld intergranular corrosion, compatible with TIG, MIG, arc and laser welding methods.

Wide Temperature Adaptability Stable mechanical performance from -196℃ cryogenic environment up to continuous working temperature 800℃.

Sanitary & Food-Grade Safe Non-toxic, no harmful metal precipitation, meets international food contact and pharmaceutical production standards.

Low Maintenance & Long Service Life Self-passivation anti-rust layer, no painting required, wear-resistant and aging-resistant.

High Cost Performance Better anti-corrosion performance than 200 series stainless steel, cheaper than 316L series, universal structural flat steel for all industries.

7. Typical Applications

7.1 Food & Sanitary Equipment Industry

Food machine support frames, kitchen equipment base plates, beverage production line brackets, seafood processing equipment fixing strips, stainless sink structural blanks.

7.2 Medical & Pharmaceutical Equipment

Pharmaceutical workshop partition frames, medical instrument structural brackets, sterile equipment supporting flat bars, laboratory anti-corrosion fixtures.

7.3 Mechanical & Automation Equipment

Automation machine base plates, fixture positioning strips, pump and valve structural parts, conveyor equipment brackets, robot connecting supports.

7.4 Architectural & Decoration Engineering

Stainless decorative strips, handrail base strips, outdoor guardrail supports, curtain wall fixed brackets, landscape engineering anti-rust structural parts, swimming pool auxiliary frames.

7.5 Chemical & Environmental Protection

Low-corrosion medium equipment brackets, sewage treatment tank supports, mild acid workshop structural frames, waste gas pipeline fixing strips.

7.6 General Hardware & Custom Processing

Hardware mold blanks, bolt and nut raw material strips, furniture anti-rust brackets, outdoor advertising frame supports, small welded structural parts.

8. Grade Comparison: 304 / 304L / 316L / 201

9. Usage Notes

Avoid long-term service in seawater, salt fog, bleach and high chloride media to prevent pitting corrosion; select 316L flat bar for coastal and marine projects.

Cold processing (rolling, cutting, bending) produces slight magnetism, which is a normal physical property and will not affect structural strength; demagnetization treatment can be provided if zero-magnetism is required.

For workpieces with frequent welding and high anti-corrosion demand, 304L low-carbon grade is recommended to eliminate weld intergranular corrosion.

Continuous working temperature shall not exceed 800℃; long-term high temperature will cause surface oxidation and decline of corrosion resistance.

After welding thick flat bars exposed to corrosive environment, pickling and passivation treatment is suggested to restore complete anti-rust performance.

10. Executive Standards & Export Supporting Certificates

Compliant with ASTM A276, ASTM A480, EN 10088-4, JIS G4303, GB/T 706, GB/T 1220. Available documents: MTC material test certificate, SGS third-party composition inspection report, RoHS environmental compliance certificate, food-grade safety test report, fully meet global export and engineering procurement standards.