440C Stainless Steel Round Bar
Grade: 440C/UNS S44004
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
440C stainless steel is a high-carbon martensitic chromium stainless steel grade designated as UNS S44004. It is one of the hardest and most wear-resistant stainless steel grades in the 400 series, specifically developed for applications requiring extremely high hardness, excellent abrasion resistance, good edge retention, and moderate corrosion resistance. Through proper heat treatment, 440C stainless steel can achieve very high hardness levels while maintaining sufficient corrosion resistance for demanding precision applications.
The alloy contains a high chromium content and elevated carbon content, which allows the formation of chromium carbides within a hardened martensitic matrix. Chromium provides corrosion resistance by forming a stable passive oxide film on the surface, while carbon contributes to the formation of hard carbides that significantly improve wear resistance, cutting performance, and dimensional stability. The combination of high chromium and carbon provides excellent resistance to abrasion and mechanical wear.
440C stainless steel bars are generally supplied in annealed condition for machining and are subsequently hardened and tempered to achieve optimum mechanical properties. After heat treatment, the material can reach hardness levels of approximately 58–60 HRC, offering outstanding wear resistance and strength. It also provides good polishing characteristics, making it suitable for precision components requiring smooth surface finishes.
Due to its exceptional hardness and wear resistance, 440C stainless steel bars are widely used in high-performance bearings, cutting tools, surgical instruments, molds, valve components, pump parts, precision machinery components, and wear-resistant mechanical assemblies. It is especially suitable for applications where maximum hardness and corrosion resistance are required, although it is less suitable for severe impact loading due to its reduced toughness compared with lower-carbon martensitic grades.
ASTM / JIS / EN Standards
| Standard System | Standard / Grade | Description |
| ASTM | ASTM A276 / A276M – UNS S44004 | Stainless Steel Bars and Shapes |
| ASTM | ASTM A580 / A580M – UNS S44004 | Stainless Steel Wire and Bar Products |
| UNS | S44004 | 440C Stainless Steel Grade |
| JIS | JIS G4303 SUS440C | Stainless Steel Bars |
| EN | EN 10088-3 1.4125 | X105CrMo17 Stainless Steel |
| DIN | DIN 1.4125 | 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 required hardness |
| 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) | 0.95 – 1.20 |
| 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 | 850–1100 MPa |
| Yield Strength (0.2% Offset) | ≥ 550 MPa |
| Elongation | ≥ 5% |
| Hardness | 58–60 HRC (Typical) |
| Condition | Hardened and Tempered |
Annealed Condition (Typical)
| Property | Requirement |
| Tensile Strength | Approximately 760 MPa |
| Hardness | ≤ 269 HB |
| Condition | Annealed |
| Industry | Applications |
| Bearing Industry | Precision bearings, bearing races, wear-resistant parts |
| Cutlery Industry | Premium knives, blades, cutting tools |
| Medical Industry | Surgical instruments, dental tools |
| Mold Industry | Plastic molds, precision dies, tooling components |
| Valve Industry | Valve seats, sealing components |
| Mechanical Engineering | Wear plates, shafts, bushings, precision components |
| Aerospace Industry | High-performance mechanical parts |
440C stainless steel is a high-carbon martensitic chromium stainless steel grade designated as UNS S44004. It is one of the hardest and most wear-resistant stainless steel grades in the 400 series, specifically developed for applications requiring extremely high hardness, excellent abrasion resistance, good edge retention, and moderate corrosion resistance. Through proper heat treatment, 440C stainless steel can achieve very high hardness levels while maintaining sufficient corrosion resistance for demanding precision applications.
The alloy contains a high chromium content and elevated carbon content, which allows the formation of chromium carbides within a hardened martensitic matrix. Chromium provides corrosion resistance by forming a stable passive oxide film on the surface, while carbon contributes to the formation of hard carbides that significantly improve wear resistance, cutting performance, and dimensional stability. The combination of high chromium and carbon provides excellent resistance to abrasion and mechanical wear.
440C stainless steel bars are generally supplied in annealed condition for machining and are subsequently hardened and tempered to achieve optimum mechanical properties. After heat treatment, the material can reach hardness levels of approximately 58–60 HRC, offering outstanding wear resistance and strength. It also provides good polishing characteristics, making it suitable for precision components requiring smooth surface finishes.
Due to its exceptional hardness and wear resistance, 440C stainless steel bars are widely used in high-performance bearings, cutting tools, surgical instruments, molds, valve components, pump parts, precision machinery components, and wear-resistant mechanical assemblies. It is especially suitable for applications where maximum hardness and corrosion resistance are required, although it is less suitable for severe impact loading due to its reduced toughness compared with lower-carbon martensitic grades.
ASTM / JIS / EN Standards
| Standard System | Standard / Grade | Description |
| ASTM | ASTM A276 / A276M – UNS S44004 | Stainless Steel Bars and Shapes |
| ASTM | ASTM A580 / A580M – UNS S44004 | Stainless Steel Wire and Bar Products |
| UNS | S44004 | 440C Stainless Steel Grade |
| JIS | JIS G4303 SUS440C | Stainless Steel Bars |
| EN | EN 10088-3 1.4125 | X105CrMo17 Stainless Steel |
| DIN | DIN 1.4125 | 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 required hardness |
| 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) | 0.95 – 1.20 |
| 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 | 850–1100 MPa |
| Yield Strength (0.2% Offset) | ≥ 550 MPa |
| Elongation | ≥ 5% |
| Hardness | 58–60 HRC (Typical) |
| Condition | Hardened and Tempered |
Annealed Condition (Typical)
| Property | Requirement |
| Tensile Strength | Approximately 760 MPa |
| Hardness | ≤ 269 HB |
| Condition | Annealed |
| Industry | Applications |
| Bearing Industry | Precision bearings, bearing races, wear-resistant parts |
| Cutlery Industry | Premium knives, blades, cutting tools |
| Medical Industry | Surgical instruments, dental tools |
| Mold Industry | Plastic molds, precision dies, tooling components |
| Valve Industry | Valve seats, sealing components |
| Mechanical Engineering | Wear plates, shafts, bushings, precision components |
| Aerospace Industry | High-performance mechanical parts |
