38Si7
1.5023Silicon spring steel with lower C (0.35-0.42%) than 55Si7 — better toughness and fatigue life at the cost of slightly lower maximum hardness. Si (1.5-1.8%) gives excellent hot sag resistance to ~250°C. THE automotive engine valve spring material in many European OEMs. Also used for clutch springs, suspension springs, and applications requiring fatigue endurance under dynamic loading.
International equivalents
| Flag | Standard | Country | Grade | Number | Match |
|---|---|---|---|---|---|
| 🇺🇸 | AISI | USA | AISI 9254 (approximate) | — | REF |
| 🇪🇺 | EN | Europe | 38Si7 / 1.5023 | 1.5023 | 100% |
Sources: ASTM A29, EN 10089
Chemical composition comparison (wt%)
Side-by-side: 38Si7 (EN 10089) vs 38Si7 / 1.5023 (EN) (EN 10089)
| Element | 38Si7 (EN 10089) | 38Si7 / 1.5023 (EN) | Overlap |
|---|---|---|---|
| C | — | 0.35–0.42% | — |
| Si | — | 1.5–1.8% | — |
Mechanical properties
Compatibility verdict
38Si7 and 38Si7 / 1.5023: 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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