440A vs 440B
These two grades are listed as equivalents of each other: their chemistry windows overlap and they serve the same applications. They are not always identical — check the differences below before substituting, especially in certified designs.
440A
Stainless Steel
440A is the lowest-carbon member of the 440 high-carbon martensitic series, trading a little attainable hardness for toughness and corrosion resistance. It is used for cutlery and dental and surgical instruments.
Standards: AISI 440A · JIS SUS440A · GB 68Cr17
440B
Stainless Steel
440B is the middle member of the 440 series, with carbon between 440A and 440C, balancing edge hardness against toughness and corrosion resistance in cutlery and bearing applications.
Standards: AISI 440B · JIS SUS440B
Chemical composition compared (%)
| Element | 440A | 440B |
|---|---|---|
| C | 0.60–0.75 | 0.75–0.95 |
| Si | ≤1.00 | ≤1.00 |
| Mn | ≤1.00 | ≤1.00 |
| P | ≤0.040 | ≤0.040 |
| S | ≤0.030 | ≤0.030 |
| Cr | 16.00–18.00 | 16.00–18.00 |
| Mo | ≤0.75 | ≤0.75 |
Properties compared
| Property | 440A | 440B |
|---|---|---|
| Delivery condition | Annealed (hardened for use) | Annealed (hardened for use) |
| Hardness (hardened) | 55–58 HRC | 56–59 HRC |
| Tensile strength | 725–1930 MPa (condition dependent) | 740–1960 MPa (condition dependent) |
| Density | 7.70 g/cm³ | 7.70 g/cm³ |
| Magnetic | Yes | Yes |
Sourcing either grade?
Nasteel stocks both families from Shenzhen with EN 10204 3.1 mill certificates by heat number.
Ask for a quotationSee full data sheets: 440A · 440B. Substitution decisions for certified parts stay with the design authority.