BS 6744 Grade 1.4429 Stainless Steel Rebar
Nitrogen-Enhanced Molybdenum-Bearing Solution for Superior Weldability and Durability
As a leading global manufacturer and exporter, Hunan Fushun Metal Co., Ltd. presents our advanced nitrogen-enhanced stainless steel reinforcing bars, manufactured to meet the stringent requirements of BS 6744. Our Grade 1.4429 rebar combines the proven chloride resistance of a molybdenum-bearing austenitic alloy with the microstructural stability provided by deliberate nitrogen alloying. This results in a reinforcement solution that offers excellent corrosion protection, enhanced mechanical properties, and outstanding weldability—making it a premium choice for critical concrete structures in the harshest environments.
With deep expertise across specialty steel products, including alloy structural steel, nickel-based alloys, and tool 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 1.4429, 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 1.4429 bar is fully traceable with a documented metallurgical history, a critical requirement of the standard.
1. Chemical Composition (Cast Analysis)
Grade 1.4429 is a nitrogen-enhanced austenitic stainless steel with a significant Molybdenum (Mo) addition, specifically engineered to deliver superior resistance to pitting corrosion while maintaining a stable austenitic microstructure. The deliberate nitrogen addition not only boosts strength but also further enhances corrosion resistance. According to BS 6744 Table 5, 1.4429 is listed among the “Alloys used for corrosion resistance to chloride ingress in concrete.” The precise cast analysis is tightly controlled within the following limits:
| Element | Requirement (% by mass, max unless range given) |
|---|---|
| Carbon (C) | 0.05 |
| Silicon (Si) | 1.0 |
| Manganese (Mn) | 2.0 |
| Sulphur (S) | 0.030 |
| Chromium (Cr) | 16.5 – 18.5 |
| Nickel (Ni) | 10.5 – 13.0 |
| Molybdenum (Mo) | 2.5 – 3.0 |
| Phosphorus (P) | 0.045 |
| Nitrogen (N) | 0.12 – 0.22 |
Note: This composition is in strict adherence to BS 6744, Table 5 for the 1.4429 designation. The 2.5–3.0% molybdenum range, combined with the 0.12–0.22% nitrogen addition, provides a premium level of chloride pitting resistance and enhanced mechanical strength compared to standard Mo-bearing grades.
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, as verified by our rigorous testing protocol.
3. Dimensions, Mass, and Tolerances
We manufacture the Grade 1.4429 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 for “austenitic with Mo addition” steels, as listed in Table 3. For example, a 20 mm bar has a nominal mass of 2.514 kg/m.
- 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 – 1.4429, 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 excellent dynamic load performance |
The nitrogen-enhanced austenitic structure of 1.4429 provides a beneficial combination of high strength, exceptional ductility, and excellent strain-hardening behavior, making it well-suited for demanding structural applications.
Ready to specify nitrogen-enhanced stainless steel rebar for superior chloride protection?
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 (1.4429)
- 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, 1.4429 is not subject to the mandatory Charpy impact testing required for duplex designations under Clause 12.12.1.
Frequently Asked Questions
How does Grade 1.4429 compare to Grade 1.4404, and when should it be specified?
While both are molybdenum-bearing austenitic stainless steels, there are two key differentiators. First, 1.4429 has a higher molybdenum content (2.5–3.0% vs 2.0–2.5%), providing enhanced resistance to pitting and crevice corrosion. Second, it features a deliberate nitrogen addition (0.12–0.22%), which further improves corrosion resistance and increases mechanical strength. Grade 1.4429 should be specified when the project demands a step above the industry-standard 1.4404 in terms of chloride resistance, particularly in severe marine splash zones or industrial environments with high chloride loading.
What role does the nitrogen addition play in 1.4429?
Nitrogen serves multiple beneficial functions in austenitic stainless steels. According to BS 6744 Table 5, 1.4429 contains 0.12–0.22% nitrogen. This element acts as a potent austenite stabilizer, enhances yield and tensile strength without compromising ductility, and significantly improves resistance to pitting and crevice corrosion. It is a key reason this grade maintains excellent weldability while offering premium corrosion performance.
Is 1.4429 rebar magnetic?
No. Grade 1.4429 is a fully austenitic stainless steel, and its microstructure means it exhibits very low magnetic permeability in the annealed condition. This characteristic makes it suitable for applications where non-magnetic materials are a design requirement, such as near sensitive scientific or medical equipment.
What are the primary applications for 1.4429 reinforcement bars?
Grade 1.4429 is specified for the most demanding chloride-exposed concrete structures where a long, maintenance-free design life is essential. Typical projects include heavily trafficked marine bridges with direct seawater splash exposure, industrial harbor facilities, coastal power plant cooling water structures, and chemical containment bunds. It is chosen when project specifications require a proven, high-molybdenum austenitic grade with excellent fabrication characteristics.
Can FUSHUN METAL supply 1.4429 rebar fabricated to BS 8666?
Yes, absolutely. Per BS 6744, Clause 11, our ribbed stainless steel bars can be supplied straight, in coils, or fabricated in accordance with BS 8666 (“Scheduling, dimensioning, bending and cutting of steel reinforcement for concrete”). The excellent formability and weldability of 1.4429 make it ideally suited for the production of complex prefabricated reinforcement cages, which we can supply directly to your project with full traceability.
Secure Your Critical Infrastructure with Nitrogen-Enhanced Durability
Contact FUSHUN METAL today to explore how our BS 6744 Grade 1.4429 nitrogen-enhanced stainless steel reinforcement can provide the extra margin of corrosion protection your critical infrastructure demands.
Specify the premium option. Nitrogen-enhanced austenitic rebar with full mill certification, verified weldability, and global project support.
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