Steel Grade Datasheet
51CrV4/ 1.8159 / 6150Chromium-Vanadium Spring / Q&T Steel
What is 51CrV4 steel?
51CrV4 (Werkstoff No. 1.8159, equivalent to AISI 6150) is a chromium-vanadium high-strength spring/Q&T steel. Its high carbon (0.47–0.55%) gives a high yield strength, while vanadium provides fine grain and superior fatigue resistance. This combination makes it the classic material for springs, torsion bars and heavily loaded Q&T parts that carry high stress without taking a permanent set. In the tempered condition it provides 900–1300 MPa tensile strength.
Chemical Composition
Cast analysis, % by weight (per the applicable EN standard)
| Element | Range (%) |
|---|---|
| C | 0.47–0.55 |
| Si | ≤ 0.40 |
| Mn | 0.70–1.10 |
| P | ≤ 0.025 |
| S | ≤ 0.025 |
| Cr | 0.90–1.20 |
| V | 0.10–0.25 |
Mechanical Properties (+QT)
Values depend on ruling section / thickness (d).
| Section (mm) | Yield Re min (MPa) | Tensile Rm (MPa) | Elongation A min (%) |
|---|---|---|---|
| d ≤ 16 | 900 | 1100–1300 | 9 |
| 16 < d ≤ 40 | 800 | 1000–1200 | 10 |
| 40 < d ≤ 100 | 700 | 900–1100 | 11 |
Hardness: +A (annealed): ≤ 248 HB · +QT: typically 270–330 HB · Spring application: ~44–50 HRC
51CrV4 / 1.8159 properties and use
International Equivalents
Values marked ≈ are nearest matches, not exact equivalents. Always confirm against the governing standard.
| System | Grade |
|---|---|
| EN | 51CrV4 |
| W.-Nr. (DIN) | 1.8159 |
| AISI/SAE | 6150 |
| ASTM | A29 / A231 (6150) |
| JIS | SUP10 |
| GOST | ≈ 50ХФА (50KhFA) |
| BS (UK) | ≈ 735A50 (EN47) |
| GB (China) | ≈ 51CrVA |
Applications
- Coil (helical) and leaf springs
- Torsion bars
- Heavily loaded Q&T parts
- Hand tools, chisels and punches
- Shafts needing high fatigue strength
- Agricultural and automotive spring elements
Available Product Forms
Frequently Asked Questions
What makes 51CrV4 a spring steel?+
Two properties: high carbon (0.5%) gives a high yield strength (the spring does not take a permanent set), and vanadium refines the grain and raises fatigue resistance. Springs deflect over millions of cycles; vanadium markedly extends this fatigue life.
What hardness does 51CrV4 reach?+
It depends on the application: for spring manufacture, quenching and tempering give ~44–50 HRC; for general Q&T parts, the target is 270–330 HB (~28–36 HRC). Hardness is set by the tempering temperature.
Is 51CrV4 the same as AISI 6150?+
For practical purposes yes; 51CrV4 is the European (EN) and 6150 the American (AISI/SAE) designation, used interchangeably as a chromium-vanadium spring steel. The JIS equivalent is SUP10. For critical work follow the ordering standard's ranges.
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References & Standards
Values on this page are reference data compiled from the applicable EN standard; certified material properties are defined by the mill test certificate (EN 10204 3.1).