Xi'an Dongmeng Group Co., Ltd. is one of the most reliable manufacturers and suppliers of aisi 347 / uns s34700 stainless steel 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.
AISI 347 stainless steel (UNS S34700), also known as 347 Austenitic Stainless Steel, Stabilized Stainless Steel with Niobium, or Nb-Stabilized 347 SS, is a high-performance heat-resistant austenitic stainless steel with excellent corrosion resistance, intergranular corrosion prevention, and high-temperature mechanical stability. As a trusted AISI 347 supplier, UNS S34700 manufacturer, and 347 stainless steel exporter, we provide sheets, plates, coils, bars, pipes, tubes, and custom-fabricated components for chemical processing, petrochemical, food processing, heat exchangers, and thermal equipment.
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High Quality
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Advanced Equipment
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Professional Team
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Custom Service
WHAT IS AISI 347 STAINLESS STEEL?
AISI 347 stainless steel is an 18-8 austenitic stainless steel (similar to 304) that is stabilized with niobium (Nb).
Key composition:
Chromium (Cr): 17–19%
Nickel (Ni): 9–13%
Niobium (Nb): Stabilizing element
👉 Niobium prevents chromium carbide formation during welding
👉 This improves resistance to intergranular corrosion
AISI 347 / UNS S34700 is a niobium-stabilized austenitic stainless steel, designed to resist intergranular corrosion after exposure to temperatures in the chromium carbide precipitation range (425–870°C). Compared to AISI 321, 347 contains niobium (Nb) instead of titanium, providing superior high-temperature strength and thermal stability.
This grade is ideal for industrial environments requiring continuous high-temperature service, oxidation resistance, and mechanical stability under thermal cycling, such as boilers, heat exchangers, chemical vessels, exhaust manifolds, and petrochemical equipment.
Project Case – Chemical Plant Application
Client Country: India
Industry: Chemical Processing
Material Supplied:
AISI 347 Stainless Steel Plate
Specification:
10mm × 1500mm × 3000mm
Requirement:
Resistance to welding corrosion
High temperature stability
Long service life in acidic environment
Our Solution:
Provided ASTM A240 certified 347 plates
Controlled niobium stabilization ratio
Full PMI + UT testing
Result:
Improved equipment durability and reduced maintenance frequency by 20%.
Export Experience
Export to 60+ countries
Widely used in chemical and energy industries
Stable supply for EPC engineering projects
Why Niobium Is Important in 347
Niobium (Nb) in 347 stainless steel:
Stabilizes carbon at high temperature
Prevents chromium carbide precipitation
Improves weld zone corrosion resistance
Enhances thermal stability after fabrication
👉 This makes 347 suitable for welded high-temperature equipment.
Processing Characteristics
Excellent weldability
Good forming performance
Suitable for high-temperature service
Not suitable for highly reducing acid environments
347 vs 304 vs 321
| Property | 304 | 321 | 347 |
|---|---|---|---|
| Stabilizer | None | Titanium | Niobium |
| High Temp Resistance | Medium | Good | Excellent |
| Weld Stability | Medium | Good | Very Good |
| Corrosion Resistance | Good | Better | Best in weld zones |
👉 Conclusion:
347 is the best choice for welded structures under high-temperature service conditions.
Standards & Compliance
AISI 347 (UNS S34700) complies with:
ASTM A240 / A312 / A276 / A479
ASME SA240
EN 1.4550
UNS S34700
Widely used in chemical, petrochemical, and power generation industries.
Chemical Composition (Typical)
| Element | % |
|---|---|
| C | ≤ 0.08 |
| Mn | ≤ 2.0 |
| Si | ≤ 1.0 |
| P | ≤ 0.045 |
| S | ≤ 0.03 |
| Cr | 17.0 – 19.0 |
| Ni | 9.0 – 13.0 |
| Nb + Ta | 10 × C min (~0.5%) |
| Fe | Balance |
Mechanical Properties
| Property | Value |
|---|---|
| Tensile Strength | ≥ 515 MPa |
| Yield Strength (0.2% offset) | ≥ 205 MPa |
| Elongation | ≥ 40% |
| Hardness | ≤ 95 HRB |
| Maximum Service Temperature | ~870°C (continuous) |
Specifications (Metric & Imperial)
Sheets / Plates / Coils
| Thickness | Width | Length |
|---|---|---|
| 0.3–80 mm | 1000 / 1219 / 1500 / 2000 mm | 2000–6000 mm |
| 0.012–3.15 in | 40–78 in | 78–236 in |
Pipes & Tubes
| Outside Diameter | Wall Thickness | Length |
|---|---|---|
| 6–630 mm | 0.5–40 mm | 1–12 m |
| 0.24–24.8 in | 0.02–1.57 in | 3–40 ft |
Bars / Rods
| Diameter | Length |
|---|---|
| 6–300 mm | 1–6 m |
| 0.24–12 in | 3–20 ft |
Tolerances
Plate: ASTM A480
Pipe: ASTM A999 / A530
Bar: ASTM A484
Custom machining available on request
Key Features
Niobium-stabilized to prevent intergranular corrosion
Excellent heat resistance and oxidation performance
High mechanical strength at elevated temperatures
Suitable for welding and fabrication
Reliable long-term performance in industrial thermal applications
Alternative to 321 in harsh chemical and high-temperature environments
Products Applications
Heat exchangers and condenser tubes
Chemical processing equipment
Petrochemical reformer and heater tubes
Boilers and pressure vessels
Exhaust systems and thermal processing equipment
Food and beverage processing equipment
Inspection & Quality Assurance
Chemical composition verification (PMI testing)
Mechanical testing: tensile, hardness, elongation
Non-destructive testing: UT, RT, ET
Surface roughness and dimensional checks
Third-party inspection available (SGS, BV, TUV)
Mill Test Certificate EN 10204 3.1 included
Product Delivery Standards
Seaworthy export packaging
Protective film + kraft paper + steel pallets
Pipe end caps and bundled packing
Reinforced container loading for long-distance shipment
Delivery options: FOB / CFR / CIF / DDP
Short lead time for stock and custom orders
We supply AISI 347 stainless steel sheets, plates, coils, pipes, tubes, bars, and custom fabrication for global industrial buyers. Contact us for quotes, samples, or technical support.
Our address
Room 4107, Runfeng Building, Sanqiao New Street, Weiyang District, Xi'an City, Shaanxi Province
Phone Number
+86 15769214734
FAQ
Q1: What is the main difference between 347 and 321 stainless steel?
A1: 347 uses niobium (Nb) stabilization instead of titanium, providing better resistance to intergranular corrosion and superior high-temperature performance.
Q2: Can AISI 347 be used for continuous high-temperature service?
A2: Yes. It is suitable for continuous service up to 870°C, making it ideal for boilers, heat exchangers, and exhaust systems.
Q3: Do you provide MTC and third-party inspection?
A3: Yes. EN 10204 3.1 MTC is included, and SGS / BV / TUV inspections are available on request.
Q4: What product forms are available for 347 stainless steel?
A4: Sheets, plates, coils, pipes, tubes, bars, and custom-fabricated components.
Q5: Can AISI 347 be welded safely?
A5: Yes. Niobium stabilization prevents sensitization and intergranular corrosion during welding.
Q6: Do you offer custom sizes or machining services?
A6: Yes. Cutting, bending, polishing, beveling, welding, and CNC machining services are available.
Q7: What are the packaging and delivery options?
A7: Standard export seaworthy packing includes waterproof film, steel pallets, pipe end caps, and reinforced container loading.
AISI 347 (UNS S34700) is a niobium-stabilized austenitic stainless steel designed for excellent weld stability, corrosion resistance, and high-temperature performance in chemical and industrial applications.
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