Steel VDCrV OT-HEAVY
Heat-treated state
GB VDCrV
Large-diameter Cr-V wire for heavy-duty valve/clutch springs; tensile drops with section size but Cr-V hardenability keeps the core fully martensitic.
Values for the OT-HEAVY condition
Other VDCrV tempers and conditions
VDCrV is listed in 6 conditions; see the grade overview at VDCrV.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Intermediate mill condition only; used when the part is cold formed and then quench-and-temper hardened by the spring maker. | 450 | 700 | 18 | 17 HRC | 8.6 % IACS |
OT-HEAVYThis page oil hardened and tempered, d > 4.0 mm (up to ~10 mm) | Large-diameter Cr-V wire for heavy-duty valve/clutch springs; tensile drops with section size but Cr-V hardenability keeps the core fully martensitic. | 1,450 | 1,620 | 8 | 47 HRC | 7.8 % IACS |
OTDefault Oil hardened and tempered wire, valve spring quality | Standard as-supplied condition for coiling high-duty valve and injector springs. | 1,570 | 1,750 | 7 | 50 HRC | 7.8 % IACS |
coiled spring, stress relieved 350–430 °C | Condition of the finished coiled spring after low-temperature stress relief; raises the elastic limit and relaxation resistance. | 1,650 | 1,780 | 7 | 50 HRC | 7.8 % IACS |
OT + SR + shot peened | Choose for maximum high-cycle fatigue life in engine valve springs; compressive surface stress lifts the endurance limit substantially. | 1,660 | 1,780 | 6 | 51 HRC | 7.8 % IACS |
OT fine gauge | Fine-diameter valve spring wire; the same heat treatment gives higher tensile because of the smaller section. | 1,690 | 1,880 | 6 | 52 HRC | 7.8 % IACS |
What is VDCrV OT-HEAVY?
VDCrV OT-HEAVY is VDCrV heat treated to OT-HEAVY — large-diameter Cr-V wire for heavy-duty valve/clutch springs; tensile drops with section size but Cr-V hardenability keeps the core fully martensitic. VDCrV OT-HEAVY has a yield strength of 1,450 MPa (210 ksi) and a tensile strength of 1,620 MPa (235 ksi) — stronger than 97% of steel grades. Elongation at break is 8% and the elastic modulus is 206 GPa (29.9 Msi). VDCrV OT-HEAVY has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F). OT is the default condition FabDigit quotes; OT-HEAVY is available on request or by drawing note.
Advantages
- High strength — 1,450 MPa (210 ksi), better than 97% of steel grades
Limitations
- Difficult to weld — 12/100, worse than 96% of steel grades
- Limited ductility — 8%, worse than 95% of steel grades
- Difficult to machine — 24/100, worse than 95% of steel grades
- Low fracture toughness — 45 MPa·√m (41 ksi·√in), worse than 90% of steel grades
- Limited service temperature — 220°C (428 °F), worse than 89% of steel grades
VDCrV OT-HEAVY properties
Typical room-temperature values for VDCrV OT-HEAVY; 22 are specific to this condition. Other listed values are VDCrV reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
VDCrV OT-HEAVY has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
VDCrV OT-HEAVY has a yield strength of 1,450 MPa (210 ksi) and a tensile strength of 1,620 MPa (235 ksi) — stronger than 97% of steel grades. Elongation at break is 8% and the elastic modulus is 206 GPa (29.9 Msi).
Thermal6
VDCrV OT-HEAVY is rated for continuous service to 220°C (428 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
VDCrV OT-HEAVY conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (14/100), better than 70% of steel grades.
Sustainability4
Producing a kilogram of VDCrV OT-HEAVY takes about 31 MJ of energy and emits 2.3 kg of CO₂ — more than 64% of steel grades. Typical recycled content is 20%.
Manufacturability7
VDCrV OT-HEAVY's machinability is poor (24/100, worse than 95% of steel grades); weldability not recommended (12/100); formability fair (35/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with VDCrV OT-HEAVY
Is VDCrV easy to machine?
Supplied at ~50 HRC — ends are ground, not turned; any machining needs CBN/ceramic tooling or is done in the annealed rod condition.
Can VDCrV be welded?
Effectively unweldable in service condition: 0.5 %C with Cr forms brittle untempered martensite; only resistance tacking of coil ends with subsequent local temper.
Can VDCrV be formed, bent or molded?
Cold coiled directly from the oil-tempered spool; keep coiling stresses moderate, then stress relieve 350–430 °C for 20–30 min and pre-set to remove initial relaxation.
What surface finishes work on VDCrV?
Shot peen for fatigue, then phosphate + oil, Zn or Zn-Ni plate (bake 190–220 °C ≥4 h against hydrogen embrittlement) or epoxy/powder coat; avoid acid pickling of finished springs.
VDCrV 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 |
|---|---|---|
| CDCrV chemistry per EN 10270-2, comparable to 50CrV4 / JIS SWOCV-V | 0.47 – 0.55 | 0.51 |
| Si | 0.15 – 0.4 | 0.27 |
| Mn | 0.6 – 1 | 0.8 |
| Cr | 0.8 – 1.2 | 1 |
| V | 0.1 – 0.25 | 0.16 |
| Pvalve spring quality — tightened limits | ≤ 0.02 | — |
| S | ≤ 0.02 | — |
| Cu | ≤ 0.12 | — |
| Fe | balance | — |
VDCrV OT-HEAVY — frequently asked
What is VDCrV OT-HEAVY used for?
VDCrV OT-HEAVY is typically used for engine valve springs, high-stress precision springs and automotive suspension components. In short: hottest-running VD grade, 220 °C; higher fatigue than plain carbon VDC; cr-V valve-spring wire.
What is the yield strength of VDCrV OT-HEAVY?
VDCrV OT-HEAVY has a typical yield strength of 1,450 MPa (210 ksi) and a tensile strength of 1,620 MPa (235 ksi) — stronger than 97% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is VDCrV OT-HEAVY easy to machine?
Not especially — machinability is rated poor (24/100, worse than 95% of steel grades). Supplied at ~50 HRC — ends are ground, not turned; any machining needs CBN/ceramic tooling or is done in the annealed rod condition.
Can VDCrV OT-HEAVY be welded?
Not readily — weldability is rated not recommended (12/100). Effectively unweldable in service condition: 0.5 %C with Cr forms brittle untempered martensite; only resistance tacking of coil ends with subsequent local temper.
What surface finishes work on VDCrV OT-HEAVY?
Shot peen for fatigue, then phosphate + oil, Zn or Zn-Ni plate (bake 190–220 °C ≥4 h against hydrogen embrittlement) or epoxy/powder coat; avoid acid pickling of finished springs.
Can VDCrV OT-HEAVY be formed, bent or molded?
Cold coiled directly from the oil-tempered spool; keep coiling stresses moderate, then stress relieve 350–430 °C for 20–30 min and pre-set to remove initial relaxation.
What is the maximum service temperature of VDCrV OT-HEAVY?
VDCrV OT-HEAVY is rated for continuous use to about 220°C (428 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between VDCrV-OT and VDCrV-ANN?
OT is the default condition — standard as-supplied condition for coiling high-duty valve and injector springs. ANN: intermediate mill condition only; used when the part is cold formed and then quench-and-temper hardened by the spring maker. Yield strength is 1,570 MPa in OT versus 450 MPa in ANN.
Sources
- EN 10270-2 — Steel wire for mechanical springs, Part 2: Oil hardened and tempered spring steel wire — CEN (2011)
- EN 10083-3 — Quenched and tempered steels, alloy steels (50CrV4) — CEN (2006)
- EN 13906-1 — Cylindrical helical springs, compression springs design — CEN (2013)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys (spring steels) — ASM International (1990)
- JIS G 3561 — Oil tempered Cr-V wire for valve springs (SWOCV-V) — JISC (2018)
- Oil hardened and tempered valve spring wire datasheets (Suzuki Garphyttan / Sandvik / Kobe Steel) — various producers (2023)
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.