440B Stainless Steel Round Bar
Grade: 440B/UNS S44003
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
440B stainless steel is a high-carbon martensitic chromium stainless steel grade designated as UNS S44003. It is developed for applications requiring a higher hardness level, improved wear resistance, and better edge retention than 440A stainless steel while maintaining good corrosion resistance. As a member of the 440 series stainless steels, 440B provides an excellent balance between hardness, strength, corrosion resistance, and toughness, making it suitable for demanding mechanical and precision applications.
The alloy contains chromium as the primary corrosion-resistant element and a higher carbon content compared with conventional martensitic stainless steels. Chromium forms a protective chromium oxide passive film that provides resistance to oxidation and mild corrosive environments. The increased carbon content allows the formation of chromium carbides during heat treatment, resulting in a hardened martensitic structure with superior wear resistance and high mechanical strength.
440B stainless steel bars are generally supplied in annealed condition for machining and can be heat treated through hardening and tempering processes to achieve high hardness levels. After heat treatment, the material offers excellent abrasion resistance, good dimensional stability, and superior cutting performance. Compared with 440A, 440B provides higher hardness and wear resistance, while compared with 440C, it offers slightly improved toughness and easier processing characteristics.
440B stainless steel bars are widely used in knife blades, surgical instruments, molds, bearings, valves, pump components, precision tools, and wear-resistant mechanical parts. The alloy is particularly suitable for applications requiring high hardness and corrosion resistance where extreme hardness levels of 440C are not necessary.
ASTM / JIS / EN Standards
| Standard System | Standard / Grade | Description |
| ASTM | ASTM A276 / A276M – UNS S44003 | Stainless Steel Bars and Shapes |
| ASTM | ASTM A580 / A580M – UNS S44003 | Stainless Steel Wire and Bar Products |
| UNS | S44003 | 440B Stainless Steel Grade |
| JIS | JIS G4303 SUS440B | Stainless Steel Bars |
| EN | EN 10088-3 1.4112 | X90CrMoV18 Stainless Steel |
| DIN | DIN 1.4112 | 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 815–900°C |
| Hardening Temperature | Approximately 1010–1065°C followed by oil or air cooling |
| Tempering Temperature | Approximately 150–370°C depending on hardness requirements |
| 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) | 0.75 – 0.95 |
| Silicon (Si) | ≤ 1.00 |
| Manganese (Mn) | ≤ 1.00 |
| Phosphorus (P) | ≤ 0.040 |
| Sulfur (S) | ≤ 0.030 |
| Chromium (Cr) | 16.00 – 18.00 |
| Molybdenum (Mo) | 0.75 |
| Nickel (Ni) | ≤ 0.60 |
| Iron (Fe) | Balance |
Mechanical Properties
Hardened and Tempered Condition (Typical)
| Property | Requirement |
| Tensile Strength | 800–1000 MPa |
| Yield Strength (0.2% Offset) | ≥ 500 MPa |
| Elongation | ≥ 8% |
| Hardness | 56–60 HRC (Typical) |
| Condition | Hardened and Tempered |
Annealed Condition (Typical)
| Property | Requirement |
| Tensile Strength | Approximately 760 MPa |
| Hardness | ≤ 269 HB |
| Condition | Annealed |
| Industry | Applications |
| Cutlery Industry | High-quality knives, blades, cutting tools |
| Medical Industry | Surgical instruments, precision medical tools |
| Bearing Industry | High-wear bearings and components |
| Mold Industry | Plastic molds, precision dies |
| Valve Industry | Valve seats, sealing components |
| Mechanical Engineering | Wear-resistant shafts, bushings, tooling parts |
| Precision Manufacturing | High-hardness precision components |
440B stainless steel is a high-carbon martensitic chromium stainless steel grade designated as UNS S44003. It is developed for applications requiring a higher hardness level, improved wear resistance, and better edge retention than 440A stainless steel while maintaining good corrosion resistance. As a member of the 440 series stainless steels, 440B provides an excellent balance between hardness, strength, corrosion resistance, and toughness, making it suitable for demanding mechanical and precision applications.
The alloy contains chromium as the primary corrosion-resistant element and a higher carbon content compared with conventional martensitic stainless steels. Chromium forms a protective chromium oxide passive film that provides resistance to oxidation and mild corrosive environments. The increased carbon content allows the formation of chromium carbides during heat treatment, resulting in a hardened martensitic structure with superior wear resistance and high mechanical strength.
440B stainless steel bars are generally supplied in annealed condition for machining and can be heat treated through hardening and tempering processes to achieve high hardness levels. After heat treatment, the material offers excellent abrasion resistance, good dimensional stability, and superior cutting performance. Compared with 440A, 440B provides higher hardness and wear resistance, while compared with 440C, it offers slightly improved toughness and easier processing characteristics.
440B stainless steel bars are widely used in knife blades, surgical instruments, molds, bearings, valves, pump components, precision tools, and wear-resistant mechanical parts. The alloy is particularly suitable for applications requiring high hardness and corrosion resistance where extreme hardness levels of 440C are not necessary.
ASTM / JIS / EN Standards
| Standard System | Standard / Grade | Description |
| ASTM | ASTM A276 / A276M – UNS S44003 | Stainless Steel Bars and Shapes |
| ASTM | ASTM A580 / A580M – UNS S44003 | Stainless Steel Wire and Bar Products |
| UNS | S44003 | 440B Stainless Steel Grade |
| JIS | JIS G4303 SUS440B | Stainless Steel Bars |
| EN | EN 10088-3 1.4112 | X90CrMoV18 Stainless Steel |
| DIN | DIN 1.4112 | 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 815–900°C |
| Hardening Temperature | Approximately 1010–1065°C followed by oil or air cooling |
| Tempering Temperature | Approximately 150–370°C depending on hardness requirements |
| 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) | 0.75 – 0.95 |
| Silicon (Si) | ≤ 1.00 |
| Manganese (Mn) | ≤ 1.00 |
| Phosphorus (P) | ≤ 0.040 |
| Sulfur (S) | ≤ 0.030 |
| Chromium (Cr) | 16.00 – 18.00 |
| Molybdenum (Mo) | 0.75 |
| Nickel (Ni) | ≤ 0.60 |
| Iron (Fe) | Balance |
Mechanical Properties
Hardened and Tempered Condition (Typical)
| Property | Requirement |
| Tensile Strength | 800–1000 MPa |
| Yield Strength (0.2% Offset) | ≥ 500 MPa |
| Elongation | ≥ 8% |
| Hardness | 56–60 HRC (Typical) |
| Condition | Hardened and Tempered |
Annealed Condition (Typical)
| Property | Requirement |
| Tensile Strength | Approximately 760 MPa |
| Hardness | ≤ 269 HB |
| Condition | Annealed |
| Industry | Applications |
| Cutlery Industry | High-quality knives, blades, cutting tools |
| Medical Industry | Surgical instruments, precision medical tools |
| Bearing Industry | High-wear bearings and components |
| Mold Industry | Plastic molds, precision dies |
| Valve Industry | Valve seats, sealing components |
| Mechanical Engineering | Wear-resistant shafts, bushings, tooling parts |
| Precision Manufacturing | High-hardness precision components |
