Steel VDSiCrV OT-N
Finish state
GB VDSiCrV
OT-N = oT + nitrided (gas/plasma) + peened
Choose when the highest surface hardness and fatigue strength are required for high-rpm or high-temperature valve springs.
Values for the OT-N condition
Other VDSiCrV tempers and conditions
VDSiCrV is listed in 7 conditions; see the grade overview at VDSiCrV.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
OT, diameter 4.0–7.0 mm | Larger diameters for clutch/suspension and heavy-duty engine springs; slightly lower tensile band. | 1,750 | 1,910 | 8 | 53 HRC | 7.5 % IACS |
OT, diameter 2.0–4.0 mm | Most commonly stocked size range for automotive valve springs. | 1,870 | 2,040 | 7 | 55 HRC | 7.5 % IACS |
OTDefault Oil hardened and tempered wire, as supplied | Standard as-delivered condition of EN 10270-2 VDSiCrV wire; coil springs directly from this state. | 1,890 | 2,060 | 7 | 55 HRC | 7.5 % IACS |
OT-NThis page OT + nitrided (gas/plasma) + peened | Choose when the highest surface hardness and fatigue strength are required for high-rpm or high-temperature valve springs. | 1,890 | 2,010 | 5 | 62 HRC | 7.5 % IACS |
OT + stress relieved after coiling | Condition of the finished spring after low-temperature stress relief; slight tensile drop, big gain in set resistance. | 1,900 | 2,010 | 7 | 54 HRC | 7.5 % IACS |
OT + stress relieved + shot peened | Production valve-spring condition: compressive surface stress from single/dual peening raises fatigue life substantially. | 1,900 | 2,010 | 6 | 55 HRC | 7.5 % IACS |
OT, diameter 1.0–2.0 mm | Fine valve-spring wire sizes with the highest tensile band; used for small high-frequency springs. | 2,000 | 2,180 | 6 | 57 HRC | 7.5 % IACS |
What is VDSiCrV OT-N?
VDSiCrV OT-N is VDSiCrV supplied in the OT-N condition — choose when the highest surface hardness and fatigue strength are required for high-rpm or high-temperature valve springs. VDSiCrV OT-N has a yield strength of 1,890 MPa (274 ksi) and a tensile strength of 2,010 MPa (292 ksi) — stronger than 99% of steel grades. Elongation at break is 5% and the elastic modulus is 206 GPa (29.9 Msi). VDSiCrV OT-N has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,420°C (2,588 °F). OT is the default condition FabDigit quotes; OT-N is available on request or by drawing note.
Advantages
- High strength — 1,890 MPa (274 ksi), better than 99% of steel grades
Limitations
- Difficult to machine — 4/100, worse than 100% of steel grades
- Difficult to weld — 3/100, worse than 100% of steel grades
- Limited formability — 5/100, worse than 99% of steel grades
- Limited ductility — 5%, worse than 98% of steel grades
- Low fracture toughness — 25 MPa·√m (22.8 ksi·√in), worse than 97% of steel grades
VDSiCrV OT-N properties
Typical room-temperature values for VDSiCrV OT-N; 21 are specific to this condition. Other listed values are VDSiCrV reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
VDSiCrV OT-N has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical15
VDSiCrV OT-N has a yield strength of 1,890 MPa (274 ksi) and a tensile strength of 2,010 MPa (292 ksi) — stronger than 99% of steel grades. Elongation at break is 5% and the elastic modulus is 206 GPa (29.9 Msi).
Thermal6
VDSiCrV OT-N is rated for continuous service to 230°C (446 °F). It conducts heat at 40 W/m·K (23.1 BTU/hr·ft·°F), worse than 64% of steel grades. Thermal expansion is 12.5 µm/m·K (6.94 µin/in·°F).
Electrical3
VDSiCrV OT-N conducts electricity at 7.5 % IACS, worse than 67% of steel grades.
Chemical & Environmental2
Corrosion resistance is poor (20/100), better than 87% of steel grades.
Sustainability4
Producing a kilogram of VDSiCrV OT-N takes about 32 MJ of energy and emits 2.3 kg of CO₂ — more than 70% of steel grades. Typical recycled content is 20%.
Manufacturability6
VDSiCrV OT-N's machinability is not recommended (4/100, worse than 100% of steel grades); weldability not recommended (3/100); formability not recommended (5/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with VDSiCrV OT-N
Is VDSiCrV easy to machine?
Supplied at ~55 HRC — not machined; ends are ground with soft wheels and coils cut by abrasive/CBN, avoiding grinding burn.
Can VDSiCrV be welded?
Effectively unweldable; welding or arc strikes create untempered martensite and are cause for rejection of spring wire.
Can VDSiCrV be formed, bent or molded?
Cold coiled in the delivered oil-tempered state on CNC coilers, then stress relieved 400–430 °C for 20–30 min; never re-austenitize.
What surface finishes work on VDSiCrV?
Shot peen (often dual peen) and hot pre-set for fatigue life; protect with phosphate+oil, epoxy or zinc-flake — avoid acid pickling and electroplating (hydrogen embrittlement) or bake immediately.
VDSiCrV chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Chigh-carbon martensitic matrix | 0.6 – 0.7 | 0.65 |
| Siraises tempering resistance and set resistance | 1.2 – 1.6 | 1.4 |
| Mn | 0.5 – 0.9 | 0.7 |
| Crhardenability, carbide stability | 0.5 – 0.8 | 0.65 |
| Vgrain refinement, stable MC carbides for heat/relaxation resistance | 0.1 – 0.2 | 0.15 |
| P | ≤ 0.02 | — |
| S | ≤ 0.02 | — |
| Cumax, residual | ≤ 0.12 | — |
| Fe | balance | — |
VDSiCrV OT-N — frequently asked
What is VDSiCrV OT-N used for?
VDSiCrV OT-N is typically used for high-performance engine valve springs, racing valve springs and critical fatigue-resistant springs. In short: highest-strength valve-spring wire; best fatigue life in series; si-Cr-V oil-tempered grade.
What is the yield strength of VDSiCrV OT-N?
VDSiCrV OT-N has a typical yield strength of 1,890 MPa (274 ksi) and a tensile strength of 2,010 MPa (292 ksi) — stronger than 99% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is VDSiCrV OT-N easy to machine?
Not especially — machinability is rated not recommended (4/100, worse than 100% of steel grades). Supplied at ~55 HRC — not machined; ends are ground with soft wheels and coils cut by abrasive/CBN, avoiding grinding burn.
Can VDSiCrV OT-N be welded?
Not readily — weldability is rated not recommended (3/100). Effectively unweldable; welding or arc strikes create untempered martensite and are cause for rejection of spring wire.
What surface finishes work on VDSiCrV OT-N?
Shot peen (often dual peen) and hot pre-set for fatigue life; protect with phosphate+oil, epoxy or zinc-flake — avoid acid pickling and electroplating (hydrogen embrittlement) or bake immediately.
Can VDSiCrV OT-N be formed, bent or molded?
Cold coiled in the delivered oil-tempered state on CNC coilers, then stress relieved 400–430 °C for 20–30 min; never re-austenitize.
What is the maximum service temperature of VDSiCrV OT-N?
VDSiCrV OT-N is rated for continuous use to about 230°C (446 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between VDSiCrV-OT and VDSiCrV OT-SR?
OT is the default condition — standard as-delivered condition of EN 10270-2 VDSiCrV wire; coil springs directly from this state. OT-SR: condition of the finished spring after low-temperature stress relief; slight tensile drop, big gain in set resistance. Yield strength is 1,890 MPa in OT versus 1,900 MPa in OT-SR.
Sources
- EN 10270-2 Steel wire for mechanical springs — Part 2: Oil hardened and tempered spring steel wire — CEN (2012)
- EN 13906-1 Cylindrical helical springs — Compression springs design — CEN (2013)
- JIS G 3561 Oil tempered Si-Cr(-V) valve spring quality steel wire (SWOSC-V / SWOSC-VV) — JSA (2016)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (spring steels) — ASM International (1990)
- Oil tempered Si-Cr-V valve spring wire datasheets — Suzuki Garphyttan / Kobe Steel / Sandvik (2022)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.