431 Stainless Steel Round Bar
Grade: 431/UNS S43100
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
431 stainless steel is a high-strength martensitic chromium-nickel stainless steel grade designated as UNS S43100. It is developed for applications requiring a combination of high tensile strength, excellent toughness, good corrosion resistance, and superior mechanical performance compared with standard martensitic stainless steels such as 410 and 420. The addition of nickel improves toughness and corrosion resistance while maintaining the ability to achieve high hardness through heat treatment.
The alloy contains chromium as the primary corrosion-resistant element and nickel as an important alloying addition. Chromium forms a protective passive oxide film that provides resistance to atmospheric corrosion, fresh water, and mild chemical environments. Nickel enhances the stability of the martensitic structure after heat treatment and improves impact toughness, ductility, and resistance to stress corrosion cracking compared with lower alloy martensitic stainless steels.
431 stainless steel bars are normally supplied in annealed condition for machining and can be heat treated by quenching and tempering to achieve high mechanical strength and hardness. After heat treatment, the material provides excellent tensile strength, good fatigue resistance, and improved wear resistance. It also maintains better corrosion resistance than many conventional hardenable stainless steels.
Due to its combination of high strength, toughness, and corrosion resistance, 431 stainless steel bars are widely used in aerospace components, marine equipment, pump shafts, valve components, fasteners, turbine parts, and mechanical engineering applications. It is particularly suitable for structural and rotating components requiring high mechanical loads, impact resistance, and reliable performance in moderately corrosive environments.
ASTM / JIS / EN Standards
| Standard System | Standard / Grade | Description |
| ASTM | ASTM A276 / A276M – UNS S43100 | Stainless Steel Bars and Shapes |
| ASTM | ASTM A479 / A479M – UNS S43100 | Stainless Steel Bars for Pressure Equipment |
| UNS | S43100 | 431 Stainless Steel Grade |
| JIS | JIS G4303 SUS431 | Stainless Steel Bars |
| EN | EN 10088-3 1.4057 | X17CrNi16-2 Stainless Steel |
| DIN | DIN 1.4057 | 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 | Annealed, Hardened and Tempered |
| Annealing Temperature | Approximately 620–670°C |
| Hardening Temperature | Approximately 980–1060°C followed by oil or air cooling |
| Tempering Temperature | Approximately 600–700°C depending on required properties |
| Surface Condition | Black Surface, Bright Surface, Ground Surface, Polished Surface |
| Dimensional Tolerance | According to ASTM A276 / customer requirements |
| Inspection | Chemical Analysis, Hardness Testing, Mechanical Testing, Dimensional Inspection |
| Supply Condition | Annealed, Heat Treated, Machined Condition |
Chemical Composition (%)
| Element | Composition Requirement |
| Carbon (C) | 0.12 – 0.22 |
| Silicon (Si) | ≤ 1.00 |
| Manganese (Mn) | ≤ 1.00 |
| Phosphorus (P) | ≤ 0.040 |
| Sulfur (S) | ≤ 0.030 |
| Chromium (Cr) | 15.00 – 17.00 |
| Nickel (Ni) | 1.25 – 2.50 |
| Molybdenum (Mo) | ≤ 0.80 |
| Iron (Fe) | Balance |
Mechanical Properties
Hardened and Tempered Condition (Typical)
| Property | Requirement |
| Tensile Strength | 850–1000 MPa |
| Yield Strength (0.2% Offset) | ≥ 650 MPa |
| Elongation | ≥ 12% |
| Hardness | 25–40 HRC (Typical) |
| Condition | Hardened and Tempered |
Annealed Condition (Typical)
| Property | Requirement |
| Tensile Strength | Approximately 800 MPa |
| Hardness | ≤ 285 HB |
| Condition | Annealed |
| Industry | Applications |
| Cutlery Industry | Knives, blades, scissors, cutting tools |
| Medical Industry | Surgical instruments, dental instruments |
| Mold Industry | Plastic molds, forming dies, tooling components |
| Mechanical Engineering | Shafts, bushings, gears, wear-resistant parts |
| Valve Industry | Valve seats, pump components, precision parts |
| Food Processing | Cutting equipment and wear-resistant components |
| Industrial Equipment | High-strength mechanical components |
431 stainless steel is a high-strength martensitic chromium-nickel stainless steel grade designated as UNS S43100. It is developed for applications requiring a combination of high tensile strength, excellent toughness, good corrosion resistance, and superior mechanical performance compared with standard martensitic stainless steels such as 410 and 420. The addition of nickel improves toughness and corrosion resistance while maintaining the ability to achieve high hardness through heat treatment.
The alloy contains chromium as the primary corrosion-resistant element and nickel as an important alloying addition. Chromium forms a protective passive oxide film that provides resistance to atmospheric corrosion, fresh water, and mild chemical environments. Nickel enhances the stability of the martensitic structure after heat treatment and improves impact toughness, ductility, and resistance to stress corrosion cracking compared with lower alloy martensitic stainless steels.
431 stainless steel bars are normally supplied in annealed condition for machining and can be heat treated by quenching and tempering to achieve high mechanical strength and hardness. After heat treatment, the material provides excellent tensile strength, good fatigue resistance, and improved wear resistance. It also maintains better corrosion resistance than many conventional hardenable stainless steels.
Due to its combination of high strength, toughness, and corrosion resistance, 431 stainless steel bars are widely used in aerospace components, marine equipment, pump shafts, valve components, fasteners, turbine parts, and mechanical engineering applications. It is particularly suitable for structural and rotating components requiring high mechanical loads, impact resistance, and reliable performance in moderately corrosive environments.
ASTM / JIS / EN Standards
| Standard System | Standard / Grade | Description |
| ASTM | ASTM A276 / A276M – UNS S43100 | Stainless Steel Bars and Shapes |
| ASTM | ASTM A479 / A479M – UNS S43100 | Stainless Steel Bars for Pressure Equipment |
| UNS | S43100 | 431 Stainless Steel Grade |
| JIS | JIS G4303 SUS431 | Stainless Steel Bars |
| EN | EN 10088-3 1.4057 | X17CrNi16-2 Stainless Steel |
| DIN | DIN 1.4057 | 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 | Annealed, Hardened and Tempered |
| Annealing Temperature | Approximately 620–670°C |
| Hardening Temperature | Approximately 980–1060°C followed by oil or air cooling |
| Tempering Temperature | Approximately 600–700°C depending on required properties |
| Surface Condition | Black Surface, Bright Surface, Ground Surface, Polished Surface |
| Dimensional Tolerance | According to ASTM A276 / customer requirements |
| Inspection | Chemical Analysis, Hardness Testing, Mechanical Testing, Dimensional Inspection |
| Supply Condition | Annealed, Heat Treated, Machined Condition |
Chemical Composition (%)
| Element | Composition Requirement |
| Carbon (C) | 0.12 – 0.22 |
| Silicon (Si) | ≤ 1.00 |
| Manganese (Mn) | ≤ 1.00 |
| Phosphorus (P) | ≤ 0.040 |
| Sulfur (S) | ≤ 0.030 |
| Chromium (Cr) | 15.00 – 17.00 |
| Nickel (Ni) | 1.25 – 2.50 |
| Molybdenum (Mo) | ≤ 0.80 |
| Iron (Fe) | Balance |
Mechanical Properties
Hardened and Tempered Condition (Typical)
| Property | Requirement |
| Tensile Strength | 850–1000 MPa |
| Yield Strength (0.2% Offset) | ≥ 650 MPa |
| Elongation | ≥ 12% |
| Hardness | 25–40 HRC (Typical) |
| Condition | Hardened and Tempered |
Annealed Condition (Typical)
| Property | Requirement |
| Tensile Strength | Approximately 800 MPa |
| Hardness | ≤ 285 HB |
| Condition | Annealed |
| Industry | Applications |
| Cutlery Industry | Knives, blades, scissors, cutting tools |
| Medical Industry | Surgical instruments, dental instruments |
| Mold Industry | Plastic molds, forming dies, tooling components |
| Mechanical Engineering | Shafts, bushings, gears, wear-resistant parts |
| Valve Industry | Valve seats, pump components, precision parts |
| Food Processing | Cutting equipment and wear-resistant components |
| Industrial Equipment | High-strength mechanical components |
