BS 6744 Grade 1.4529 Stainless Steel Rebar
Ultimate Austenitic Protection for the Most Corrosive Industrial and Marine Environments
As a leading global manufacturer and exporter, Hunan Fushun Metal Co., Ltd. presents our supreme super austenitic stainless steel reinforcing bars, manufactured to meet the stringent requirements of BS 6744. Our Grade 1.4529 rebar stands at the apex of corrosion-resistant concrete reinforcement, delivering extraordinary resistance to pitting, crevice corrosion, and stress corrosion cracking in environments where even premium duplex grades may falter. For critical infrastructure exposed to hot seawater, aggressive chemical process streams, and severe industrial pollutants, FUSHUN METAL provides the material engineered to endure.
With deep expertise across specialty steel products, including alloy structural steel, nickel-based alloys, and mould steel, and full compliance with international benchmarks like ASTM, EN, DIN, and JIS, we guarantee that our BS 6744-compliant reinforcement bars offer unparalleled quality and performance. This introduction focuses on our ribbed stainless steel bar, steel designation 1.4529 (super austenitic, 6% Mo), in strength grade 500.
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Technical Specifications & Compliance
Our reinforcement bars are produced and tested strictly in accordance with BS 6744, which specifies the requirements for solid stainless steel bars used for concrete reinforcement. This standard is applicable to ribbed bars in grade 500, where ribs are formed by cold working or hot rolling processes. FUSHUN METAL’s Grade 1.4529 bar is fully traceable with a documented metallurgical history, a critical requirement of the standard.
1. Chemical Composition (Cast Analysis)
Grade 1.4529 is a super austenitic stainless steel with an extraordinarily high alloy content, featuring exceptional levels of Nickel, Molybdenum, and deliberate additions of Copper and Nitrogen. Often referred to as a 6% Molybdenum alloy, this grade is engineered for the most severe corrosion challenges known to civil engineering. According to BS 6744 Table 5, 1.4529 is listed under the “Alloys used for special applications” category, where specialist corrosion advice might be required to specify. The precise cast analysis is tightly controlled within the following limits:
| Element | Requirement (% by mass, max unless range given) |
|---|---|
| Carbon (C) | 0.02 |
| Silicon (Si) | 0.50 |
| Manganese (Mn) | 1.0 |
| Sulphur (S) | 0.010 |
| Chromium (Cr) | 19.0 – 21.0 |
| Nickel (Ni) | 24.0 – 26.0 |
| Molybdenum (Mo) | 6.0 – 7.0 |
| Copper (Cu) | 0.50 – 1.50 |
| Phosphorus (P) | 0.030 |
| Nitrogen (N) | 0.15 – 0.25 |
Note: This composition is in strict adherence to BS 6744, Table 5 for the 1.4529 designation. The exceptionally high nickel content (24.0–26.0%) ensures a fully austenitic and thermally stable microstructure, while the 6.0–7.0% molybdenum and copper addition provides unequalled resistance to pitting and crevice corrosion, particularly in hot, acidified chloride solutions.
2. Heat Treatment Condition
Our ribbed stainless steel bars are supplied in one of the following conditions as per BS 6744, Clause 11, ensuring optimal mechanical properties and surface finish:
- Hot rolled and descaled
- Hot rolled, descaled, and decooled
The carefully controlled manufacturing process guarantees that the product is free from detrimental phases and intergranular corrosion. The high nickel content ensures microstructural stability during thermal processing.
3. Dimensions, Mass, and Tolerances
We manufacture the Grade 1.4529 rebar in a wide range of standard diameters, from 6 mm to 50 mm, in full compliance with the standard. The dimensional characteristics are precisely controlled to ensure a perfect bond with concrete.
Standard Diameters
The following nominal diameters are available as standard for the 500 strength grade, as specified in BS 6744, Clause 5 and Table 2:
| Grade | Nominal Diameters (mm) |
|---|---|
| 500 | 6, 7, 8, 10, 12, 14, 16, 20, 25, 32, 40, 50 |
Note: Non-standard diameters may also be available upon request.
- Nominal Length
- Agreed upon at the time of order, with a standard permissible deviation of +100/0 mm or as per BS 8666.
- Nominal Mass per Meter Run
- Calculated according to BS EN ISO 15630, our bars strictly conform to the specified nominal mass per meter. Given the high nickel and molybdenum content, the density of 1.4529 is higher than standard austenitic grades. For precise mass values, please refer to the manufacturer’s certification.
- Tolerances on Mass
- Stringent tolerances are applied, ranging from ±9.0% for a 6 mm bar to ±4.5% for bars over 12 mm in diameter.
4. Grade & Mechanical Properties (Strength Level 500, Ductility Class B)
Our reinforcing bars are designated as strength grade 500 and consistently achieve the mechanical properties for Ductility Class B as defined in BS 6744, Table 8.
| Property | Requirement |
|---|---|
| Designation | BS 6744 – 1.4529, B500B |
| Characteristic Yield Strength (fyk) | 500 MPa |
| 0.2% Proof Strength (Rp0.2) | 500 MPa minimum |
| Tensile Strength (Rm) | Meets the minimum value for the stress ratio |
| Stress Ratio (Rm/Rp0.2) | ≥ 1.08 |
| Total Elongation at Max Force (Agt) | ≥ 5.0% |
| Elongation After Fracture (A5) | ≥ 14% |
| Bendability | Passes 180° bend test around a former of max diameter specified (e.g., 4d for d≤16 mm, 7d for d>16 mm) |
| Fatigue Strength | Withstands 5 × 106 cycles of stress at a stress ratio of 0.2 without fracture, ensuring superior dynamic load performance |
The super austenitic structure provides exceptional ductility and toughness, making this grade highly suitable for seismic regions and structures subject to extreme loading conditions.
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Request a Quote5. Surface Geometry & Bonding
Ensuring a strong mechanical interlock with concrete is paramount. Our bars feature rows of crescent-shaped transverse ribs that meet the geometric criteria of BS 6744, Clause 10:
- Relative Rib Area (fR): Exceeds the minimum relative rib area (fRmin) specified in Table 6, which is the ruling criterion for bond performance.
- Rib Flank Inclination (α): Measured at ≥ 45°, ensuring effective load transfer without splitting the concrete cover.
- Transverse Rib Projection: Extends over at least 80% of the bar’s periphery.
These geometric properties are measured and verified in accordance with BS EN ISO 15630-1.
6. Packaging and Product Identification
Every product from FUSHUN METAL is meticulously packaged and labelled to guarantee complete traceability and compliance.
- Product Marking
- Each bar is identified by rolled-on legible marks on the surface at intervals not greater than 1.5 meters, identifying the manufacturer as specified by the standard.
- Bundle / Coil Labelling
- Each bundle or coil is firmly attached with a durable label containing all the mandatory information per BS 6744, Clause 13.2:
- Standard Reference (BS 6744)
- Steel Designation (1.4529)
- Nominal Diameter
- Strength Grade (500)
- Ductility Class (B)
- Durability Class
- Cast Number and Batch Reference
- Manufacturer’s Name (FUSHUN METAL)
7. Inspection & Test Report
Quality assurance is non-negotiable. Our products are tested at a frequency of one test per ten tonnes from each production batch. Every shipment is accompanied by a detailed test certificate as per Clause 12.3, which includes:
- The complete cast analysis for all specified elements.
- Results of the tensile test (including effective cross-sectional area), confirming 0.2% proof strength, stress ratio, and elongation properties.
- Results of the bend test.
- Intergranular corrosion test results (one test per batch), in accordance with BS EN ISO 3651-2.
- Confirmation of durability class and the manufacturer’s rolled-on mark.
- A statement of conformity to BS 6744.
Note: As an austenitic grade, 1.4529 is not subject to the mandatory Charpy impact testing required for duplex designations under Clause 12.12.1, although its toughness is inherently excellent.
Frequently Asked Questions
What elevates Grade 1.4529 above all other grades in BS 6744 for corrosion resistance?
Grade 1.4529 is classified by BS 6744 Table 5 as an “Alloy used for special applications” and its chemistry is uniquely formidable. It features 6.0–7.0% Molybdenum, 24.0–26.0% Nickel, and deliberate Copper (0.50–1.50%) additions. This combination produces a PREN typically exceeding 50, providing resistance to seawater at all temperatures, including hot seawater brines. The copper addition specifically enhances resistance to corrosion in acidic, reducing environments such as flue gas desulfurization plants and chemical processing facilities.
Why is the Nickel content so high in 1.4529, and what benefit does this provide?
The exceptionally high nickel content (24.0–26.0%) ensures a completely stable austenitic microstructure, eliminating the risk of forming sigma or chi phases during welding or thermal cycling. This guarantees that the outstanding corrosion resistance is maintained throughout the entire fabrication process. It also provides excellent ductility and toughness, critical for structures in seismic zones or those subject to impact loading.
What are the definitive applications where only 1.4529 should be specified?
According to BS 6744 Table 5, this grade is reserved for “special applications, e.g. where the steel may be exposed” to conditions beyond the capability of standard or duplex grades. Definitive applications include warm seawater outfalls and intakes in the Middle East and other high-salinity, high-temperature regions, flue gas desulfurization (FGD) scrubbers in power plants, chemical dosing and containment structures handling hot, chlorinated process streams, and offshore platform structural elements in tropical waters.
How does 1.4529 compare to the super duplex grade 1.4501 in terms of application?
Both are premium alloys for the most severe environments, but they address different limitations. 1.4501 is a super duplex stainless steel chosen for its combination of very high strength and excellent corrosion resistance. 1.4529 is a super austenitic grade chosen for its superior corrosion resistance in the most aggressive chemical conditions, particularly hot chloride environments and reducing acids—areas where duplex grades can be challenged. It also offers superior formability and is non-magnetic, which may be a critical design requirement.
Is specialist advice really necessary to specify 1.4529, as noted in the standard?
Yes, the note in BS 6744 Table 5 that “specialist corrosion advice might be required to specify” is an important recommendation. Grade 1.4529 represents a significant investment, and its selection should be based on a detailed analysis of the specific environmental exposure, including chloride concentration, pH, temperature, and the presence of other aggressive species. FUSHUN METAL’s technical team is available to collaborate with your corrosion and structural engineering consultants to validate that 1.4529 is the correct and most cost-effective life-cycle choice for your project.
Deliver an Uncompromising Service Life in the Most Corrosive Environments
Contact FUSHUN METAL today to discuss how our BS 6744 Grade 1.4529 super austenitic stainless steel reinforcement can deliver an uncompromising, maintenance-free service life for your project in the world’s most corrosive environments.
Specify the apex material. Super austenitic 6% Mo rebar with full mill certification, specialist technical support, and dedicated global logistics.
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