255 Stainless Steel Round Bar
Grade: 255/UNS S32550
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
- Fast Shipping / Ready Stock
- ISO 9001 Direct Factory
- Custom Cutting & Processing
- 100% MTC & SGS Inspection Supported
255 stainless steel is a super duplex stainless steel grade designated as UNS S32550. It was developed as a high-performance duplex stainless steel combining the excellent corrosion resistance of stainless steels with the high strength and toughness of duplex alloys. The material has a balanced microstructure consisting of approximately equal amounts of ferrite and austenite phases, providing superior mechanical properties compared with conventional austenitic stainless steels.
UNS S32550 contains approximately 25% chromium, 5–6% nickel, 3% molybdenum, and copper additions. The high chromium content provides excellent resistance to general corrosion and oxidation, while molybdenum improves resistance to pitting and crevice corrosion. Copper enhances resistance to sulfuric acid and other reducing acid environments. Nitrogen additions improve strength, phase stability, and resistance to localized corrosion.
255 stainless steel bars offer a unique combination of high tensile strength, excellent corrosion resistance, good impact toughness, and superior resistance to chloride stress corrosion cracking. Compared with 2205 duplex stainless steel, Ferralium 255 provides higher mechanical strength and improved corrosion resistance in certain acidic and chloride-containing environments. Compared with 2507 super duplex stainless steel, it offers excellent machinability and good weldability while maintaining high corrosion performance.
The material is normally supplied in solution annealed condition to maintain the required ferrite-austenite balance. Heat treatment and fabrication procedures must be carefully controlled to prevent the formation of harmful intermetallic phases such as sigma phase, which may reduce toughness and corrosion resistance.
255 stainless steel bars are widely used in chemical processing equipment, offshore oil and gas components, marine engineering, pumps, valves, fasteners, heat exchangers, pressure vessels, and high-strength corrosion-resistant mechanical components.
ASTM / JIS / EN Standards
| Standard System | Standard / Grade | Description |
| ASTM | ASTM A276 / A276M – UNS S32550 | Stainless Steel Bars and Shapes |
| ASTM | ASTM A479 / A479M – UNS S32550 | Stainless Steel Bars for Pressure Equipment |
| ASTM | ASTM A182 – UNS S32550 | Forged Stainless Steel Components |
| UNS | S32550 | Ferralium® 255 Super Duplex Stainless Steel |
| JIS | No direct equivalent | Super Duplex Stainless Steel Grade |
| EN | EN 10088-3 1.4507 | X2CrNiMoCuN25-6-3 Stainless Steel |
| DIN | DIN 1.4507 | 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 |
| Solution Treatment Temperature | Approximately 1020–1100°C followed by rapid cooling |
| Microstructure | Approx. 50% Ferrite + 50% Austenite |
| Surface Condition | Black Surface, Bright Surface, Ground Surface, Polished Surface |
| Dimensional Tolerance | According to ASTM A276 / ASTM A479 |
| Inspection | Chemical Analysis, Mechanical Testing, Ferrite Measurement, Corrosion Testing |
| Supply Condition | Solution Annealed Condition |
Chemical Composition (%)
| Element | Composition Requirement |
| Carbon (C) | ≤ 0.040 |
| Silicon (Si) | ≤ 1.00 |
| Manganese (Mn) | ≤ 1.50 |
| Phosphorus (P) | ≤ 0.040 |
| Sulfur (S) | ≤ 0.030 |
| Chromium (Cr) | 24.00 – 27.00 |
| Nickel (Ni) | 4.50 – 6.50 |
| Molybdenum (Mo) | 2.90 – 3.90 |
| Copper (Cu) | 1.50 – 2.50 |
| Nitrogen (N) | 0.10 – 0.25 |
| Iron (Fe) | Balance |
Mechanical Properties
Solution Annealed Condition
| Property | Requirement |
| Tensile Strength | ≥ 760 MPa |
| Yield Strength (0.2% Offset) | ≥ 550 MPa |
| Elongation | ≥ 15% |
| Hardness | ≤ 310 HB |
| Impact Toughness | Excellent |
| Ferrite Content | Typically 40–60% |
| Industry | Applications |
| Oil & Gas Industry | Offshore platforms, pumps, valves, piping components |
| Chemical Industry | Acid processing equipment, reactors, heat exchangers |
| Marine Industry | Seawater pumps, shafts, marine fasteners |
| Petrochemical Industry | Pressure vessels, process equipment |
| Mining Industry | Corrosion-resistant equipment |
| Power Generation | Cooling systems, heat exchangers |
| Mechanical Engineering | High-strength shafts, bolts, precision components |
255 stainless steel is a super duplex stainless steel grade designated as UNS S32550. It was developed as a high-performance duplex stainless steel combining the excellent corrosion resistance of stainless steels with the high strength and toughness of duplex alloys. The material has a balanced microstructure consisting of approximately equal amounts of ferrite and austenite phases, providing superior mechanical properties compared with conventional austenitic stainless steels.
UNS S32550 contains approximately 25% chromium, 5–6% nickel, 3% molybdenum, and copper additions. The high chromium content provides excellent resistance to general corrosion and oxidation, while molybdenum improves resistance to pitting and crevice corrosion. Copper enhances resistance to sulfuric acid and other reducing acid environments. Nitrogen additions improve strength, phase stability, and resistance to localized corrosion.
255 stainless steel bars offer a unique combination of high tensile strength, excellent corrosion resistance, good impact toughness, and superior resistance to chloride stress corrosion cracking. Compared with 2205 duplex stainless steel, Ferralium 255 provides higher mechanical strength and improved corrosion resistance in certain acidic and chloride-containing environments. Compared with 2507 super duplex stainless steel, it offers excellent machinability and good weldability while maintaining high corrosion performance.
The material is normally supplied in solution annealed condition to maintain the required ferrite-austenite balance. Heat treatment and fabrication procedures must be carefully controlled to prevent the formation of harmful intermetallic phases such as sigma phase, which may reduce toughness and corrosion resistance.
255 stainless steel bars are widely used in chemical processing equipment, offshore oil and gas components, marine engineering, pumps, valves, fasteners, heat exchangers, pressure vessels, and high-strength corrosion-resistant mechanical components.
ASTM / JIS / EN Standards
| Standard System | Standard / Grade | Description |
| ASTM | ASTM A276 / A276M – UNS S32550 | Stainless Steel Bars and Shapes |
| ASTM | ASTM A479 / A479M – UNS S32550 | Stainless Steel Bars for Pressure Equipment |
| ASTM | ASTM A182 – UNS S32550 | Forged Stainless Steel Components |
| UNS | S32550 | Ferralium® 255 Super Duplex Stainless Steel |
| JIS | No direct equivalent | Super Duplex Stainless Steel Grade |
| EN | EN 10088-3 1.4507 | X2CrNiMoCuN25-6-3 Stainless Steel |
| DIN | DIN 1.4507 | 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 |
| Solution Treatment Temperature | Approximately 1020–1100°C followed by rapid cooling |
| Microstructure | Approx. 50% Ferrite + 50% Austenite |
| Surface Condition | Black Surface, Bright Surface, Ground Surface, Polished Surface |
| Dimensional Tolerance | According to ASTM A276 / ASTM A479 |
| Inspection | Chemical Analysis, Mechanical Testing, Ferrite Measurement, Corrosion Testing |
| Supply Condition | Solution Annealed Condition |
Chemical Composition (%)
| Element | Composition Requirement |
| Carbon (C) | ≤ 0.040 |
| Silicon (Si) | ≤ 1.00 |
| Manganese (Mn) | ≤ 1.50 |
| Phosphorus (P) | ≤ 0.040 |
| Sulfur (S) | ≤ 0.030 |
| Chromium (Cr) | 24.00 – 27.00 |
| Nickel (Ni) | 4.50 – 6.50 |
| Molybdenum (Mo) | 2.90 – 3.90 |
| Copper (Cu) | 1.50 – 2.50 |
| Nitrogen (N) | 0.10 – 0.25 |
| Iron (Fe) | Balance |
Mechanical Properties
Solution Annealed Condition
| Property | Requirement |
| Tensile Strength | ≥ 760 MPa |
| Yield Strength (0.2% Offset) | ≥ 550 MPa |
| Elongation | ≥ 15% |
| Hardness | ≤ 310 HB |
| Impact Toughness | Excellent |
| Ferrite Content | Typically 40–60% |
| Industry | Applications |
| Oil & Gas Industry | Offshore platforms, pumps, valves, piping components |
| Chemical Industry | Acid processing equipment, reactors, heat exchangers |
| Marine Industry | Seawater pumps, shafts, marine fasteners |
| Petrochemical Industry | Pressure vessels, process equipment |
| Mining Industry | Corrosion-resistant equipment |
| Power Generation | Cooling systems, heat exchangers |
| Mechanical Engineering | High-strength shafts, bolts, precision components |
