30CrMoV9
1.7707THE Cr-Mo-V nitriding steel — Cr 2.3-2.7% forms hard CrN nitrided case (800 HV surface). V addition for secondary hardening. Core QT to UTS 1080-1270 MPa before nitriding at 570-580°C. Used for piston rods, valve stems, cylinder liners, turbine parts, and any component needing extreme surface hardness + fatigue resistance without distortion (low nitriding temp).
International equivalents
| Flag | Standard | Country | Grade | Number | Match |
|---|---|---|---|---|---|
| 🇪🇺 | EN | Europe | 30CrMoV9 / 1.7707 | 1.7707 | 100% |
Sources: EN 10085
Chemical composition comparison (wt%)
Side-by-side: 30CrMoV9 (EN) (EN 10085) vs 30CrMoV9 / 1.7707 (EN) (EN 10085)
| Element | 30CrMoV9 (EN) | 30CrMoV9 / 1.7707 (EN) | Overlap |
|---|---|---|---|
| C | 0.26–0.34% | 0.26–0.34% | OK |
| Si | 0–0.4% | 0–0.4% | OK |
| Mn | 0.4–0.7% | 0.4–0.7% | OK |
| Cr | 2.3–2.7% | 2.3–2.7% | OK |
| Mo | 0.15–0.25% | 0.15–0.25% | OK |
| V | 0.1–0.2% | 0.1–0.2% | OK |
Mechanical properties
QT
| Property | Value | Unit |
|---|---|---|
| Tensile Strength | 1080–1270 | MPa |
| Yield Strength | ≥ 880 | MPa |
| Elongation | ≥ 10 | % |
| Elastic Modulus | ≥ 210 | GPa |
| Density | ≥ 7.85 | g/cm3 |
Nitrided
| Property | Value | Unit |
|---|---|---|
| hardness_hv | ≥ 800 | HV |
Heat treatment
| Process | Temperature | Medium | Holding Time | Notes |
|---|---|---|---|---|
| hardening | 850–880 °C | oil | — | Oil quench |
| tempering | 570–680 °C | air | 1-2h | Before nitriding |
| nitriding | 570–580 °C | gas/plasma | 20-80h | Case depth 0.2-0.6mm, 800 HV surface |
Compatibility verdict
30CrMoV9 and 30CrMoV9 / 1.7707: 100% composition match
Close equivalents but NOT identical.
Related materials
50CrV4
1.8160Chromium-vanadium spring/tool steel — identical alloy system to 51CrV4 (1.8159) but recognized as a separate grade in some standards. Dual use: heavy-duty springs (EN 10089) AND cold work tools (knives, shear blades). V improves temper resistance and grain refinement. UTS 1200-1500 QT. Used for heavy leaf springs, stabilizer bars, torsion bars, and cold work cutting tools.
51CrMoV4
1.7701CrMoV alloyed spring steel — THE European automotive suspension spring material. CrMo gives deep hardenability for large coil springs, V adds grain refinement and secondary hardening for fatigue resistance. UTS 1350-1600 MPa QT. Used for hot-formed coil springs (cars, trucks), leaf springs, torsion bars, and stabilizer bars. Excellent sag resistance to 200°C.
20MnCr5
1.7147Manganese-chromium case-hardening steel with higher core strength than 16MnCr5. Used for heavily loaded gears, shafts, camshafts, and transmission components requiring high surface hardness with tough core. Popular in automotive and heavy machinery.
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