Steel VDC
GB VDC
VDC is an unalloyed carbon, oil hardened and tempered valve-spring quality wire to EN 10270-2, made with tight dimensional and surface control for precision springs.
Reference datasheet — VDC is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the OT condition
VDC tempers and conditions
VDC is supplied in 7 conditions, soft to hard. OT is the default FabDigit quotes; the values on this page are for it.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
OT, diameter > 6.00–10.00 mm | Largest VDC sizes; choose an alloyed grade (VDCrV/VDSiCr) if full through-hardening or higher stress is required. | 1,410 | 1,600 | 8 | 46 HRC | 8.6 % IACS |
OT, diameter > 4.00–6.00 mm | Medium-heavy wire; strength drops with section due to reduced hardenability of the plain-carbon grade. | 1,480 | 1,680 | 7 | 48 HRC | 8.6 % IACS |
OTDefault Oil hardened and tempered, as supplied | Standard stocked condition: quenched-and-tempered wire ready for cold coiling of medium-size valve/clutch springs. | 1,560 | 1,770 | 6 | 50 HRC | 8.6 % IACS |
Stress relieved | Condition of the finished spring after coiling and low-temperature stress relief — raises elastic limit and sets free length. | 1,620 | 1,750 | 5 | 49 HRC | 8.6 % IACS |
Shot peened (+ stress relieved) spring | Pick for high-cycle valve springs: compressive surface stress lifts fatigue limit 20–35 % over unpeened wire. | 1,630 | 1,750 | 6 | 50 HRC | 8.6 % IACS |
OT, diameter > 1.00–2.00 mm | Common size band for small engine valve springs and control springs. | 1,640 | 1,860 | 5.5 | 52 HRC | 8.6 % IACS |
OT, diameter 0.50–1.00 mm | Fine wire for small precision valve springs; highest strength band of the VDC table. | 1,700 | 1,930 | 5 | 53 HRC | 8.6 % IACS |
What is VDC?
VDC is an unalloyed carbon, oil hardened and tempered valve-spring quality wire to EN 10270-2, made with tight dimensional and surface control for precision springs. Default oil-tempered properties are about 1560 MPa yield, 1770 MPa tensile and 50 HRC, with diameter bands from 0.5 mm to 10 mm and stress-relieved (SR) or shot-peened (SP) deliveries. Its limits are a maximum service temperature of about 150 °C, no weldability, and no machinability at hardness. For higher fatigue strength or hotter service, move to VDCrV or VDSiCr. VDC 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). VDC has a yield strength of 1,560 MPa (226 ksi) and a tensile strength of 1,770 MPa (257 ksi) — stronger than 98% of steel grades. Elongation at break is 6% and the elastic modulus is 206 GPa (29.9 Msi).
What is VDC used for?
- engine valve springs
- precision compression springs
- small mechanical springs
Advantages
- High strength — 1,560 MPa (226 ksi), better than 98% of steel grades
Limitations
- Limited service temperature — 150°C (302 °F), worse than 99% of steel grades
- Difficult to machine — 12/100, worse than 99% of steel grades
- Difficult to weld — 10/100, worse than 99% of steel grades
- Limited ductility — 6%, worse than 97% of steel grades
- Low fracture toughness — 25 MPa·√m (22.8 ksi·√in), worse than 97% of steel grades
VDC properties
Typical room-temperature values for VDC-OT; bars are the position among steel grades.
Physical3
VDC 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).
Mechanical15
VDC has a yield strength of 1,560 MPa (226 ksi) and a tensile strength of 1,770 MPa (257 ksi) — stronger than 98% of steel grades. Elongation at break is 6% and the elastic modulus is 206 GPa (29.9 Msi).
Thermal6
VDC is rated for continuous service to 150°C (302 °F). It conducts heat at 46 W/m·K (26.6 BTU/hr·ft·°F), better than 71% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
VDC conducts electricity at 8.6 % IACS, better than 66% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of VDC takes about 30 MJ of energy and emits 2.2 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 20%.
Manufacturability7
VDC's machinability is not recommended (12/100, worse than 99% of steel grades); weldability not recommended (10/100); formability fair (45/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. VDC is highlighted; hover a dot for its name, or open the interactive family chart.
Working with VDC
Is VDC easy to machine?
Supplied at ~50 HRC — not machined; ends are ground with CBN/alumina wheels and coolant to avoid grinding burns and re-hardened white layers.
Can VDC be welded?
Effectively unweldable: high carbon plus quenched martensite gives cracking and destroys the temper; use mechanical hooks or ground/closed ends instead.
Can VDC be formed, bent or molded?
Cold coiled directly from the OT coil on CNC coilers, then stress relieved at 250–400 °C; keep index above ~4 and avoid nicks, as surface defects control spring life.
VDC 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 |
|---|---|---|
| Cunalloyed valve-spring quality | 0.6 – 0.75 | 0.68 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 0.6 – 0.9 | 0.75 |
| Ptighter than FDC/TDC | ≤ 0.02 | |
| Stighter than FDC/TDC | ≤ 0.02 | |
| Crresidual | ≤ 0.1 | |
| Curesidual | ≤ 0.12 | |
| Niresidual | ≤ 0.12 | |
| Fe | balance |
What surface finishes work on VDC?
Shot peen and preset for fatigue, then phosphate + oil, zinc or zinc-nickel plating or epoxy paint; always bake at ~200 °C after acid pickling/plating to relieve hydrogen.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Black / Phosphate
Thermal Spray
How much does VDC cost?
VDC is a standard-cost steel ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
VDC — frequently asked
What is VDC used for?
VDC is typically used for engine valve springs, precision compression springs and small mechanical springs. In short: entry-level valve-spring wire; unalloyed carbon OT grade; lowest-cost VD quality.
What is the yield strength of VDC?
VDC has a typical yield strength of 1,560 MPa (226 ksi) and a tensile strength of 1,770 MPa (257 ksi) — stronger than 98% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is VDC easy to machine?
Not especially — machinability is rated not recommended (12/100, worse than 99% of steel grades). Supplied at ~50 HRC — not machined; ends are ground with CBN/alumina wheels and coolant to avoid grinding burns and re-hardened white layers.
Can VDC be welded?
Not readily — weldability is rated not recommended (10/100). Effectively unweldable: high carbon plus quenched martensite gives cracking and destroys the temper; use mechanical hooks or ground/closed ends instead.
What surface finishes work on VDC?
Shot peen and preset for fatigue, then phosphate + oil, zinc or zinc-nickel plating or epoxy paint; always bake at ~200 °C after acid pickling/plating to relieve hydrogen.
Can VDC be formed, bent or molded?
Cold coiled directly from the OT coil on CNC coilers, then stress relieved at 250–400 °C; keep index above ~4 and avoid nicks, as surface defects control spring life.
What is the maximum service temperature of VDC?
VDC is rated for continuous use to about 150°C (302 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between VDC-OT and VDC-SP?
OT is the default condition — standard stocked condition: quenched-and-tempered wire ready for cold coiling of medium-size valve/clutch springs. SP: pick for high-cycle valve springs: compressive surface stress lifts fatigue limit 20–35 % over unpeened wire. Yield strength is 1,560 MPa in OT versus 1,630 MPa in SP.
How much does VDC cost?
VDC is a standard-cost steel ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- EN 10270-2 — Steel wire for mechanical springs, Part 2: Oil hardened and tempered spring steel wire — CEN (2011)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys (spring steels) — ASM International (1990)
- Oil tempered valve spring wire datasheets (Suzuki Garphyttan / Bekaert / Kiswire) — various producers (2023)
- SMI Handbook of Spring Design — Spring Manufacturers Institute (2013)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.