304 (UNS S30400) Stainless Steel Reinforcement Bars
The world's most widely used stainless steel now meets the rigorous demands of concrete reinforcement. FUSHUN METAL (Hunan Fushun Metal Co., Ltd.), a global manufacturer and exporter of specialty steel products, produces 304 (UNS S30400) deformed and plain stainless steel reinforcement bars in full conformance with ASTM A955/A955M — the standard specification for deformed and plain stainless steel bars for concrete reinforcement. With production governed by ASTM, EN, DIN, and JIS standards, our 304 reinforcement bars deliver the proven corrosion resistance and mechanical reliability that engineers have trusted for decades.
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Chemical Composition
The renowned corrosion resistance of 304 stainless steel originates from its carefully balanced chemistry. FUSHUN METAL conducts a heat analysis from test samples taken during the pouring or casting of every heat, ensuring full compliance with the requirements of ASTM A955/A955M Table 2 for UNS S30400.
| Element | Composition % |
|---|---|
| Carbon (C) | 0.08 max. |
| Manganese (Mn) | 2.00 max. |
| Phosphorus (P) | 0.045 max. |
| Sulfur (S) | 0.030 max. |
| Silicon (Si) | 1.00 max. |
| Chromium (Cr) | 18.00 – 20.00 |
| Nickel (Ni) | 8.00 – 10.50 |
| Nitrogen (N) | 0.10 max. |
This classic 18-8 austenitic stainless steel grade is listed in ASTM A955/A955M among the typical alloys that have found the most use in North America. Its high chromium and nickel content provides excellent general corrosion resistance, good oxidation resistance, and outstanding formability and weldability. Compared to nickel-based alloys used in extreme environments, 304 offers a cost-effective solution for a broad range of concrete reinforcement applications. When required by the purchaser, a product analysis can be performed and will conform to the tolerances specified in ASTM A484/A484M.
Heat Treatment Condition
The mechanical properties of 304 reinforcement bars are directly governed by the heat treatment condition at the time of manufacture. FUSHUN METAL supplies bars in the following conditions, as defined in ASTM A276 and referenced by ASTM A955/A955M:
- Annealed (A)
- Hot Rolled (HR)
- Strain Hardened (B)
The choice of heat treatment condition is a critical design parameter, as it determines the baseline strength and ductility of the finished product. Any further heat treatment applied after delivery may alter the as-supplied properties. As referenced by the standard, no re-treatment should be performed without retesting to the full requirements of ASTM A955/A955M.
Size
FUSHUN METAL manufactures 304 deformed bars across the complete range of standard bar designation numbers listed in ASTM A955/A955M Table 1. The nominal dimensions of a deformed bar correspond to a plain round bar of equal weight per foot.
| Bar Designation No. | Nominal Diameter, in. [mm] | Nominal Weight, lb/ft [kg/m] (300 Series) |
|---|---|---|
| 3 [10] | 0.375 [9.5] | 0.378 [0.562] |
| 4 [13] | 0.500 [12.7] | 0.686 [1.021] |
| 5 [16] | 0.625 [15.9] | 1.058 [1.575] |
| 6 [19] | 0.750 [19.1] | 1.511 [2.248] |
| 7 [22] | 0.875 [22.2] | 2.059 [3.064] |
| 8 [25] | 1.000 [25.4] | 2.713 [4.037] |
| 9 [29] | 1.128 [28.7] | 3.341 [5.106] |
| 10 [32] | 1.270 [32.3] | 4.358 [6.484] |
| 11 [36] | 1.410 [35.8] | 5.352 [7.964] |
| 14 [43] | 1.693 [43.0] | 7.72 [11.49] |
| 18 [57] | 2.257 [57.3] | 13.72 [20.43] |
Plain rounds in diameters up to and including 2 in. [50.8 mm] are also available for use as dowels, spirals, and structural ties. Bars are supplied in standard or custom-cut lengths to meet project requirements.
Grade (Strength Level)
304 bars are produced in three minimum yield strength grades, as prescribed in ASTM A955/A955M. Tensile properties are verified on full-section specimens, with unit stress calculated on the nominal cross-sectional area.
| Grade | Tensile Strength, min | Yield Strength, min |
|---|---|---|
| Grade 40 [300] | 70,000 psi [500 MPa] | 40,000 psi [300 MPa] |
| Grade 60 [420] | 90,000 psi [620 MPa] | 60,000 psi [420 MPa] |
| Grade 75 [520] | 100,000 psi [690 MPa] | 75,000 psi [520 MPa] |
Yield strength is determined at 0.35% strain using the autographic diagram method or with an extensometer, in accordance with ASTM A370. Elongation requirements vary by bar size and grade, as defined in ASTM A955/A955M Table 3. The desired grade must be clearly specified at the time of order.
Packaging
FUSHUN METAL ensures that all 304 reinforcement bars are properly separated and tagged with the manufacturer's heat or test identification number at the time of mill shipment. Each bundle is tagged with the following information:
- Stainless steel alloy (304 / UNS S30400)
- Heat treatment condition
- Grade (minimum strength level)
- Supplementary requirement status (S1, if applicable)
When packaging procedures are specified in the purchase order, they conform to ASTM A700. For U.S. Government procurement, packaging complies with MIL-STD-163, and marking for shipment meets Fed. Std. No. 123 for civil agencies or MIL-STD-129 for military agencies. Every deformed bar is legibly marked on one side with the manufacturer's mill designation and the bar size designation. Plain rounds do not require rolled-on symbols; all required information is provided on the bundle tag.
Inspection
The purchaser's inspector is granted free entry at all times during contract execution to all areas of the manufacturer's works related to the production of the ordered material. FUSHUN METAL provides access to all reasonable facilities to verify that the material conforms to ASTM A955/A955M. All inspection and testing are performed at the manufacturing site prior to shipment and are conducted in a manner that does not unnecessarily interfere with plant operations.
Test
For each heat, bar size, and heat treatment condition, FUSHUN METAL performs the following tests as a minimum:
- One tension test — conducted on the full bar section, evaluated against the specified grade requirements for tensile strength, yield strength, and elongation.
- One bend test — performed on the full bar section, with the specimen bent around a pin to the degree and pin diameter prescribed in ASTM A955/A955M Table 4, without cracking on the outside radius.
- One set of dimensional property tests — including bar weight, and measurements of deformation spacing, average height, and gap, all verified against the limits in ASTM A955/A955M Table 1.
Deformation spacing is averaged from a minimum of ten spaces. Average height is determined from three measurements per deformation on at least two typical deformations. The measured weight of any deformed bar shall be at least 94% of the value specified in Table 1. If a test specimen fails due to mechanical reasons or inherent flaws, a replacement specimen is permitted. When a failure meets the retest provisions, two additional random specimens are tested. When Supplementary Requirement S1 is invoked for controlled magnetic permeability, testing is performed in accordance with ASTM A342 with limits agreed between manufacturer and purchaser.
Report
FUSHUN METAL issues a Material Test Report, Certificate of Inspection, or equivalent document for every order. Reports are generated on a per-heat or per-lot basis and contain:
- Stainless steel type and designation (304 / UNS S30400)
- Chemical composition (heat analysis, and product analysis if performed)
- Heat treatment condition
- Bar size
- Tensile properties (tensile strength, yield strength, elongation)
- Bend test results
- Corrosion test results (when specified)
- Magnetic permeability results (when Supplementary Requirement S1 is invoked)
Documents transmitted via electronic data interchange (EDI) carry the same validity as printed versions. The EDI-transmitted document meets all requirements of ASTM A955/A955M, and the organization submitting the transmission is responsible for its content.
Frequently Asked Questions
Why choose 304 stainless steel over carbon steel for concrete reinforcement?
304 stainless steel provides far superior corrosion resistance compared to conventional carbon steel reinforcement, particularly in environments exposed to moisture, chlorides, or atmospheric pollutants. This translates into significantly extended service life, reduced maintenance costs, and improved long-term structural integrity for critical infrastructure such as bridges, marine structures, and parking garages.
How does 304 compare to higher-alloy stainless steels like XM-29 or 316L in reinforcement applications?
304 offers a balanced combination of performance and cost. Its 18% chromium and 8% nickel content delivers excellent general corrosion resistance suitable for a wide range of environments. For extremely aggressive chloride-rich conditions, higher-alloy alternatives may offer additional pitting resistance. Our engineering team can help you evaluate which grade best fits your specific exposure conditions and project budget.
Is 304 reinforcement bar readily weldable in the field?
Yes. 304 stainless steel possesses excellent weldability, typically requiring minimal pre-weld and post-weld procedures compared to some other grades. ASTM A955/A955M recommends establishing a suitable welding procedure. We advise consulting with FUSHUN METAL regarding appropriate welding parameters and considering post-weld retesting of physical properties when welding is a significant part of fabrication.
Can 304 reinforcement bars be supplied with non-magnetic properties for specialized applications?
Yes. When low magnetic permeability is a project requirement — such as in medical imaging facilities, laboratories, or sensitive electronic installations — Supplementary Requirement S1 can be invoked in your purchase order. FUSHUN METAL will then produce and test the bars to ASTM A342, with specific permeability limits established by mutual agreement prior to production.
Source 304 Reinforcement Bars from FUSHUN METAL
FUSHUN METAL (Hunan Fushun Metal Co., Ltd.) is a trusted global manufacturer of alloy steel, nickel-based alloys, stainless steel, and tool steel. Our products serve demanding industries worldwide, backed by full compliance with international standards including ASTM, EN, DIN, and JIS. For inquiries and technical support on 304 (UNS S30400) reinforcement bars, Request a Quote and let our team deliver the quality and reliability your project demands.
