55Si7 vs 9255
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.
55Si7
Alloy & Engineering Steel
55Si7 (1.5026) is the classic silicon spring steel of EN 10089: 1.6–2.0% silicon raises the elastic limit and temper resistance, giving leaf and coil springs their fatigue life at moderate cost. It is the European counterpart of the AISI 9255/9260 family.
Standards: DIN 1.5026 (55Si7) · AISI 9255 (near) · JIS SUP7 (near) · GB 55Si2Mn (near)
9255
Alloy & Engineering Steel
9255 is a Si-Cr spring steel combining the sag resistance of silicon with chromium hardenability. It serves coil and leaf springs that are too thick for plain Si-Mn grades to harden through.
Standards: DIN 1.5026 (55Si7 family, near) · AISI 9255 · JIS SUP7 (near) · GB 55Si2Mn (near)
Chemical composition compared (%)
| Element | 55Si7 | 9255 |
|---|---|---|
| C | 0.52–0.60 | 0.51–0.59 |
| Si | 1.60–2.00 | 1.20–1.60 |
| Mn | 0.60–0.90 | 0.70–0.90 |
| P | ≤0.025 | ≤0.035 |
| S | ≤0.025 | ≤0.040 |
| Cr | — | 0.70–0.90 |
Properties compared
| Property | 55Si7 | 9255 |
|---|---|---|
| Delivery condition | Annealed or quenched & tempered | — |
| Tensile strength (Q&T) | 1250–1550 MPa (typ.) | — |
| Density | 7.85 g/cm³ | 7.85 g/cm³ |
| Hardness (spring temper) | — | 40–48 HRC typical |
| Tensile strength | — | 1200–1500 MPa (Q&T spring temper, typ.) |
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: 55Si7 · 9255. Substitution decisions for certified parts stay with the design authority.