55Si7
1.0904Silicon spring steel — Si (1.5-2.0%) provides high elastic limit and excellent fatigue resistance without expensive Cr/V additions. Better heat resistance than Cr-spring steels — retains spring properties to ~250°C. Used for valve springs, clutch springs, hot-wound coil springs, and applications with moderate elevated temperature exposure. Cheaper than CrV spring steels.
International equivalents
| Flag | Standard | Country | Grade | Number | Match |
|---|---|---|---|---|---|
| 🇺🇸 | AISI | USA | AISI 9255 (approximate) | — | REF |
| 🇪🇺 | EN | Europe | 55Si7 / 1.0904 | 1.0904 | 100% |
Sources: ASTM A29, EN 10089
Chemical composition comparison (wt%)
Side-by-side: 55Si7 (EN 10089) vs 55Si7 / 1.0904 (EN) (EN 10089)
| Element | 55Si7 (EN 10089) | 55Si7 / 1.0904 (EN) | Overlap |
|---|---|---|---|
| C | — | 0.52–0.59% | — |
| Si | — | 1.5–2% | — |
Mechanical properties
Compatibility verdict
55Si7 and 55Si7 / 1.0904: 100% composition match
Related materials
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1.7225High-strength quenched and tempered chromium-molybdenum steel. Widely used for shafts, gears, crankshafts, connecting rods, and high-strength bolts. Excellent hardenability and good fatigue resistance.
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16MnCr5
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