34CrAlNi7
1.8550THE classic aluminum-containing nitriding steel — Al 0.8-1.2% forms extremely hard AlN nitrided layer (900-1100 HV surface). Cr 1.0-1.3% + Ni 0.85-1.15% provide core strength. Highest achievable surface hardness of all nitriding steels. Used for cylinder liners, piston rings, crankshafts, spindles, and gauges where maximum nitrided hardness is critical. Also known as 34CrAlNi7-10.
International equivalents
| Flag | Standard | Country | Grade | Number | Match |
|---|---|---|---|---|---|
| 🇪🇺 | EN | Europe | 34CrAlNi7-10 / 1.8550 | 1.8550 | 100% |
Sources: EN 10085
Chemical composition comparison (wt%)
Side-by-side: 34CrAlNi7 (EN) (EN 10085) vs 34CrAlNi7-10 / 1.8550 (EN) (EN 10085)
| Element | 34CrAlNi7 (EN) | 34CrAlNi7-10 / 1.8550 (EN) | Overlap |
|---|---|---|---|
| C | 0.3–0.37% | 0.3–0.37% | OK |
| Mn | 0.4–0.7% | 0.4–0.7% | OK |
| Cr | 1–1.3% | 1–1.3% | OK |
| Mo | 0.15–0.25% | 0.15–0.25% | OK |
| Ni | 0.85–1.15% | 0.85–1.15% | OK |
| Al | 0.8–1.2% | 0.8–1.2% | OK |
Mechanical properties
QT
| Property | Value | Unit |
|---|---|---|
| Tensile Strength | 830–1030 | MPa |
| Yield Strength | 590–740 | MPa |
| Elongation | 12–16 | % |
| Elastic Modulus | ≥ 210 | GPa |
| Density | ≥ 7.85 | g/cm3 |
Nitrided
| Property | Value | Unit |
|---|---|---|
| hardness_hv | 900–1100 | HV |
Heat treatment
| Process | Temperature | Medium | Holding Time | Notes |
|---|---|---|---|---|
| hardening | 850–880 °C | oil | — | Before nitriding |
| tempering | 550–650 °C | air | 2h | Temper above nitriding temp |
| nitriding | 500–530 °C | gas/plasma | 30-90h | 900-1100 HV surface, 0.2-0.5mm case |
Compatibility verdict
34CrAlNi7 and 34CrAlNi7-10 / 1.8550: 100% composition match
Close equivalents but NOT identical.
Related materials
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51CrMoV4
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20MnCr5
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