55Si7
Data verified55Si7 (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.
Chemical composition
| Element | Content (%) |
|---|---|
| C | 0.52–0.60 |
| Si | 1.60–2.00 |
| Mn | 0.60–0.90 |
| P | ≤0.025 |
| S | ≤0.025 |
Weight percent, per the governing standard ranges. Actual values per heat are on the mill certificate.
Properties
| Delivery condition | Annealed or quenched & tempered |
| Tensile strength (Q&T) | 1250–1550 MPa (typ.) |
| Density | 7.85 g/cm³ |
Heat treatment
Harden 830–860 °C in oil; temper 350–500 °C to the spring hardness specified (typically 40–48 HRC).
Equivalent grades
| Standard | Designation |
|---|---|
| din | 1.5026 (55Si7) |
| aisi | 9255 (near) |
| jis | SUP7 (near) |
| gb | 55Si2Mn (near) |
Compare side by side: 55Si7 vs 9260 · 55Si7 vs 9255 · 55Si7 vs 60Si2Mn
Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.
Applications & Processing
Applications: Leaf springs, coil springs, stabilizer bars, torsion bars, spring washers and clips.
Processing: Decarburization-sensitive — heat in a controlled atmosphere or allow machining stock; shot peening after tempering extends fatigue life.
FAQ
- 55Si7 or 51CrV4 for a spring?
- 55Si7 is cheaper and ideal for flat/leaf springs and large coils; 51CrV4 (6150 type) gives better hardenability and fatigue performance in highly stressed round-wire and automotive springs.
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Ask for a quotationVisit NasteelSource: EN 10089 published ranges · Last updated 2026-11-03. Data is indicative — verify critical values against the governing standard and mill certificate before use.