AISI 440 and 440C stainless steel balls are high-carbon martensitic stainless steels that can be hardened to achieve excellent wear resistance and high load capacity. 440C provides higher hardness and is widely used in precision bearing and high-performance applications.
Also known as bearing-grade stainless steel balls, 440 and 440C are used in applications requiring high hardness, wear resistance and moderate corrosion resistance.
AISI 440 and 440C stainless steel balls are manufactured from high-carbon martensitic stainless steel and can be heat treated to achieve high hardness and wear resistance.
Compared with 420 stainless steel, 440C offers improved wear resistance, fatigue strength and load capacity, making it suitable for precision bearings and high-performance mechanical systems.
| Item | Specification |
| Material | AISI 440 / 440C |
| Equivalent Materials | 440: SUS440 / 9Cr18 / EN 1.4112; 440C: SUS440C / 9Cr18Mo / EN 1.4125 |
| Size Range | 0.5 mm – 200 mm |
| Hardness (Hardened & Tempered) | 440: 55–60 HRC / 440C: 58–66 HRC |
| Grade | G10 – G1000 |
| Density | 7.75 g/cm³ |
| Standard | ISO 3290 |
| Heat Treatment | Through-hardened and tempered |
| Corrosion Resistance | Moderate corrosion resistance for hardened martensitic stainless steel; lower than 304 / 316 |
| Packing | Carton / Steel drum / Bulk bag / Custom |
| Condition | Hardened, cleaned and oiled |
| Delivery Time | Stock available for standard sizes or 30–35 days for production |
| Grade | C (%) | Si (%) | Mn (%) | Cr (%) | Mo (%) | P (%) | S (%) |
| 440 | 0.90–1.00 | ≤0.80 | ≤0.80 | 17.00–19.00 | — | ≤0.035 | ≤0.030 |
| 440C | 0.95–1.20 | ≤1.00 | ≤1.00 | 16.00–18.00 | ≤0.75 | ≤0.040 | ≤0.030 |
Note: Typical chemical composition ranges. Minor variations may exist among different international standards.
