51CrV4
1.8159Chromium-vanadium spring steel. The most important European spring steel grade. Excellent fatigue resistance and high elastic limit after heat treatment. Used for coil springs, leaf springs, torsion bars, anti-roll bars, and high-strength fasteners.
International equivalents
| Flag | Standard | Country | Grade | Number | Match |
|---|---|---|---|---|---|
| 🇺🇸 | AISI | USA | AISI 6150 | G61500 | REF |
| 🇪🇺 | EN | Europe | 51CrV4 | 1.8159 | 100% |
| 🇪🇺 | DIN | Europe | 50CrV4 (old) | — | 99% |
| 🇨🇳 | GB | China | 50CrVA | — | 93% |
| 🇯🇵 | JIS | Japan | SUP10 | — | 90% |
Sources: ASTM A29, EN 10089:2002, DIN 17221, GB/T 1222, JIS G4801
Chemical composition comparison (wt%)
Side-by-side: 51CrV4 (EN) (EN 10089:2002) vs AISI 6150 (AISI) (ASTM A29)
| Element | 51CrV4 (EN) | AISI 6150 (AISI) | Overlap |
|---|---|---|---|
| C | 0.47–0.55% | 0.48–0.53% | OK |
| Si | 0–0.4% | — | — |
| Mn | 0.7–1.1% | 0.7–0.9% | OK |
| P | 0–0.025% | 0–0.035% | OK |
| S | 0–0.025% | 0–0.04% | OK |
| Cr | 0.9–1.2% | 0.8–1.1% | Partial ⚠️ AISI upper limit 0.1% lower |
| V | 0.1–0.25% | ≥ 0.15% | OK |
Mechanical properties
QT
| Property | Value | Unit |
|---|---|---|
| Tensile Strength | 1100–1300 | MPa |
| Yield Strength | ≥ 900 | MPa |
| Elongation | ≥ 9 | % |
| Hardness HRC | 36–42 | HRC |
| Elastic Modulus | ≥ 210 | GPa |
| Density | ≥ 7.85 | g/cm3 |
Heat treatment
| Process | Temperature | Medium | Holding Time | Notes |
|---|---|---|---|---|
| quenching | 830–860 °C | oil | min 30 min | Oil quench standard for spring steels |
| tempering | 400–500 °C | air | min 60 min | Spring temper: 420-480°C for optimal elastic properties |
| annealing | 680–720 °C | furnace | Several hours | Soft annealing |
Compatibility verdict
51CrV4 and AISI 6150: 93% composition match
Close equivalents but NOT identical. Critical differences: C range (0.47–0.55 vs 0.48–0.53), Mn range (0.7–1.1 vs 0.7–0.9), P range (0–0.025 vs 0–0.035), S range (0–0.025 vs 0–0.04).
For dual certification, melt must hit: C 0.48–0.53, Mn 0.7–0.9, P 0–0.025, S 0–0.025
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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