347 Stainless Steel Round Bar
Grade: 347/UNS S34700
Size:
Cold drawn: φ4mm-φ60mm
Hot Rolled: φ16mm-φ230mm
Forged: φ230mm-φ1200mm
Surface Finish: Black Annealed, Polished Bright, Centerless Grinding
Diameter Tolerance: H9, H11, h9, h11 etc
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- ISO 9001 Direct Factory
- Custom Cutting & Processing
- 100% MTC & SGS Inspection Supported
347 stainless steel is a columbium (niobium)-stabilized austenitic chromium-nickel stainless steel grade designated as UNS S34700. It was developed to provide improved resistance to intergranular corrosion after exposure to high temperatures during welding, fabrication, or long-term service. The addition of niobium stabilizes the carbon content by forming niobium carbide, preventing chromium carbide precipitation at grain boundaries and maintaining corrosion resistance in welded structures.
The alloy contains chromium and nickel as the primary alloying elements, with niobium added as a stabilizing element. Chromium provides excellent oxidation resistance and general corrosion resistance by forming a protective passive oxide film. Nickel maintains the austenitic structure, providing excellent toughness, ductility, and resistance to thermal shock. Niobium improves resistance to sensitization and allows the material to maintain stable performance in elevated-temperature environments.
347 stainless steel bars provide excellent creep strength, oxidation resistance, and mechanical stability at high temperatures. The material is suitable for continuous service temperatures up to approximately 870°C and intermittent service at higher temperatures. Compared with standard 304 stainless steel, 347 stainless steel offers improved performance after welding and prolonged exposure to high temperatures.
347 stainless steel bars are widely used in aerospace components, chemical processing equipment, power generation systems, petroleum refining equipment, heat exchangers, furnace components, and high-temperature pressure applications. The alloy is particularly suitable for welded structures and components exposed to repeated heating and cooling cycles where long-term reliability and resistance to intergranular corrosion are required.
ASTM / JIS / EN Standards
| Standard System | Standard / Grade | Description |
| ASTM | ASTM A276 / A276M – UNS S34700 | Stainless Steel Bars and Shapes |
| ASTM | ASTM A479 / A479M – UNS S34700 | Stainless Steel Bars for Pressure Equipment |
| UNS | S34700 | 347 Stainless Steel Grade |
| JIS | JIS G4303 SUS347 | Stainless Steel Bars |
| EN | EN 10088-3 1.4550 | X6CrNiNb18-10 Stainless Steel |
| DIN | DIN 1.4550 | Equivalent European Material Designation |
Stainless Steel Bar Execution Standards
| Item | Specification |
| Product Type | Round Bar, Square Bar, Hexagonal Bar |
| Manufacturing Process | Hot Rolled, Cold Drawn, Peeled, Ground, Polished |
| Heat Treatment | Solution Annealing |
| Heat Treatment Temperature | Approximately 980–1150°C followed by rapid cooling |
| Surface Condition | Black Surface, Bright Surface, Ground Surface, Polished Surface |
| Dimensional Tolerance | According to ASTM A276 / customer requirements |
| Inspection | Chemical Analysis, Mechanical Testing, Dimensional Inspection |
| Supply Condition | Solution Annealed, Cold Finished, Machined Condition |
Chemical Composition (%)
| Element | Composition Requirement |
| Carbon (C) | ≤ 0.08 |
| Silicon (Si) | ≤ 1.00 |
| Manganese (Mn) | ≤ 2.00 |
| Phosphorus (P) | ≤ 0.045 |
| Sulfur (S) | ≤ 0.030 |
| Chromium (Cr) | 17.00 – 19.00 |
| Nickel (Ni) | 9.00 – 13.00 |
| Niobium + Tantalum (Nb+Ta) | ≥ 10 × C (max 1.00) |
| Nitrogen (N) | ≤ 0.10 |
| Iron (Fe) | Balance |
Mechanical Properties (Annealed Condition)
| Property | Requirement |
| Tensile Strength | ≥ 515 MPa |
| Yield Strength (0.2% Offset) | ≥ 205 MPa |
| Elongation | ≥ 40% |
| Hardness | ≤ 201 HB (Typical) |
| Condition | Solution Annealed |
| Industry | Applications |
| Aerospace Industry | Aircraft exhaust components, engine parts, heat-resistant structures |
| Power Generation | Boiler components, steam piping, turbine parts |
| Chemical Industry | Chemical reactors, welded process equipment |
| Petroleum Industry | Refinery equipment, high-temperature piping systems |
| Heat Treatment Industry | Furnace parts, heating elements supports |
| Pressure Equipment | Pressure vessels, heat exchangers |
| Mechanical Engineering | High-temperature precision machined components |
347 stainless steel is a columbium (niobium)-stabilized austenitic chromium-nickel stainless steel grade designated as UNS S34700. It was developed to provide improved resistance to intergranular corrosion after exposure to high temperatures during welding, fabrication, or long-term service. The addition of niobium stabilizes the carbon content by forming niobium carbide, preventing chromium carbide precipitation at grain boundaries and maintaining corrosion resistance in welded structures.
The alloy contains chromium and nickel as the primary alloying elements, with niobium added as a stabilizing element. Chromium provides excellent oxidation resistance and general corrosion resistance by forming a protective passive oxide film. Nickel maintains the austenitic structure, providing excellent toughness, ductility, and resistance to thermal shock. Niobium improves resistance to sensitization and allows the material to maintain stable performance in elevated-temperature environments.
347 stainless steel bars provide excellent creep strength, oxidation resistance, and mechanical stability at high temperatures. The material is suitable for continuous service temperatures up to approximately 870°C and intermittent service at higher temperatures. Compared with standard 304 stainless steel, 347 stainless steel offers improved performance after welding and prolonged exposure to high temperatures.
347 stainless steel bars are widely used in aerospace components, chemical processing equipment, power generation systems, petroleum refining equipment, heat exchangers, furnace components, and high-temperature pressure applications. The alloy is particularly suitable for welded structures and components exposed to repeated heating and cooling cycles where long-term reliability and resistance to intergranular corrosion are required.
ASTM / JIS / EN Standards
| Standard System | Standard / Grade | Description |
| ASTM | ASTM A276 / A276M – UNS S34700 | Stainless Steel Bars and Shapes |
| ASTM | ASTM A479 / A479M – UNS S34700 | Stainless Steel Bars for Pressure Equipment |
| UNS | S34700 | 347 Stainless Steel Grade |
| JIS | JIS G4303 SUS347 | Stainless Steel Bars |
| EN | EN 10088-3 1.4550 | X6CrNiNb18-10 Stainless Steel |
| DIN | DIN 1.4550 | Equivalent European Material Designation |
Stainless Steel Bar Execution Standards
| Item | Specification |
| Product Type | Round Bar, Square Bar, Hexagonal Bar |
| Manufacturing Process | Hot Rolled, Cold Drawn, Peeled, Ground, Polished |
| Heat Treatment | Solution Annealing |
| Heat Treatment Temperature | Approximately 980–1150°C followed by rapid cooling |
| Surface Condition | Black Surface, Bright Surface, Ground Surface, Polished Surface |
| Dimensional Tolerance | According to ASTM A276 / customer requirements |
| Inspection | Chemical Analysis, Mechanical Testing, Dimensional Inspection |
| Supply Condition | Solution Annealed, Cold Finished, Machined Condition |
Chemical Composition (%)
| Element | Composition Requirement |
| Carbon (C) | ≤ 0.08 |
| Silicon (Si) | ≤ 1.00 |
| Manganese (Mn) | ≤ 2.00 |
| Phosphorus (P) | ≤ 0.045 |
| Sulfur (S) | ≤ 0.030 |
| Chromium (Cr) | 17.00 – 19.00 |
| Nickel (Ni) | 9.00 – 13.00 |
| Niobium + Tantalum (Nb+Ta) | ≥ 10 × C (max 1.00) |
| Nitrogen (N) | ≤ 0.10 |
| Iron (Fe) | Balance |
Mechanical Properties (Annealed Condition)
| Property | Requirement |
| Tensile Strength | ≥ 515 MPa |
| Yield Strength (0.2% Offset) | ≥ 205 MPa |
| Elongation | ≥ 40% |
| Hardness | ≤ 201 HB (Typical) |
| Condition | Solution Annealed |
| Industry | Applications |
| Aerospace Industry | Aircraft exhaust components, engine parts, heat-resistant structures |
| Power Generation | Boiler components, steam piping, turbine parts |
| Chemical Industry | Chemical reactors, welded process equipment |
| Petroleum Industry | Refinery equipment, high-temperature piping systems |
| Heat Treatment Industry | Furnace parts, heating elements supports |
| Pressure Equipment | Pressure vessels, heat exchangers |
| Mechanical Engineering | High-temperature precision machined components |
