347 Stainless Steel Round Bar (UNS S34700)
347 Stainless Steel Round Bar (UNS S34700) is a niobium (columbium) stabilized austenitic stainless steel developed to provide excellent resistance to intergranular corrosion during exposure to elevated temperatures. Stabilization with niobium prevents chromium carbide precipitation, making 347 round bars suitable for welding and continuous service in the temperature range where unstabilized grades may fail. This grade offers good oxidation resistance, reliable mechanical strength, and excellent performance in high-temperature and pressure environments.
Key Features
- UNS Number: S34700
- Niobium stabilized for resistance to intergranular corrosion
- Excellent strength and oxidation resistance at elevated temperatures
- Good weldability without post-weld heat treatment
- Suitable for continuous high-temperature service
- Good corrosion resistance in many industrial environments
Equivalent Grades
| Standard | Equivalent Grade |
|---|---|
| ASTM / ASME | 347 |
| UNS | S34700 |
| EN | 1.4550 |
| DIN | X6CrNiNb18-10 |
| JIS | SUS 347 |
Sizes
- Diameter Range: 3 mm to 500 mm
- Length: 3 m, 6 m, or as per customer requirement
- Custom cut-to-length sizes available
347 Stainless Steel Chemical Composition
| Element | Percentage (%) |
|---|---|
| Carbon (C) | ≤ 0.08 |
| Chromium (Cr) | 17.0 – 19.0 |
| Nickel (Ni) | 9.0 – 13.0 |
| Niobium + Tantalum (Nb + Ta) | ≥ 10 × C |
| Manganese (Mn) | ≤ 2.00 |
| Silicon (Si) | ≤ 1.00 |
| Phosphorus (P) | ≤ 0.045 |
| Sulfur (S) | ≤ 0.030 |
| Iron (Fe) | Balance |
UNS S34700 Mechanical Properties
| Property | Value |
|---|---|
| Tensile Strength | ≥ 515 MPa |
| Yield Strength (0.2% Offset) | ≥ 205 MPa |
| Elongation | ≥ 40% |
| Hardness | ≤ 217 HB |
347 Physical Properties
| Property | Value |
|---|---|
| Density | 8.0 g/cm³ |
| Melting Point | 1400 – 1425°C |
| Thermal Conductivity | 16.3 W/m·K |
| Electrical Resistivity | 0.72 µΩ·m |
| Modulus of Elasticity | 193 GPa |
Types of 347 Stainless Steel Round Bar
- Hot Rolled 347 Round Bar
- Cold Drawn 347 Round Bar
- Bright Bar
- Polished Round Bar
- Centerless Ground Round Bar
Applications
- Heat exchangers and superheaters
- Boiler components and pressure vessels
- Oil & gas refinery equipment
- Chemical processing plants
- Aircraft exhaust systems
- High-temperature piping systems
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