Steel FDCrV-OT
Heat-treated state · default condition
OT = oil hardened and tempered wire, as supplied
Standard as-drawn-and-oil-tempered coil for cold-coiled static-duty compression, extension and torsion springs.
Values for the OT condition
Other FDCrV tempers and conditions
FDCrV is listed in 6 conditions; see the grade overview at FDCrV.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Supply state for parts to be machined, hot-coiled or cold-formed and then quenched and tempered by the user. | 450 | 700 | 18 | 210 HB | — |
Quenched and tempered | Use for hot-coiled heavy springs, torsion bars and machined spring components made from the same Cr-V chemistry. | 900 | 1,100 | 10 | 35 HRC | — |
OTDefaultThis page Oil hardened and tempered wire, as supplied | Standard as-drawn-and-oil-tempered coil for cold-coiled static-duty compression, extension and torsion springs. | 1,520 | 1,700 | 7 | 49 HRC | — |
Shaved (peeled) oil-tempered wire, improved surface | Pick when decarburised/seam-free surface is needed and a step up in fatigue life is required without moving to VD grade. | 1,530 | 1,700 | 7 | 49 HRC | 8 % IACS |
oil tempered, coiled and stress-relieved (250–420 °C) | Standard finished-spring condition: stress relief after coiling restores elastic limit and reduces set/relaxation. | 1,580 | 1,720 | 6 | 49 HRC | 8 % IACS |
OT + SR + shot peened spring | Choose when the static-grade wire must survive occasional dynamic loading — peening adds compressive surface stress. | 1,580 | 1,720 | 6 | 50 HRC | 8 % IACS |
What is FDCrV-OT?
FDCrV-OT is FDCrV heat treated to OT — standard as-drawn-and-oil-tempered coil for cold-coiled static-duty compression, extension and torsion springs. FDCrV-OT has a yield strength of 1,520 MPa (220 ksi) and a tensile strength of 1,700 MPa (247 ksi) — stronger than 97% of steel grades. Elongation at break is 7% and the elastic modulus is 206 GPa (29.9 Msi). FDCrV-OT has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Advantages
- High strength — 1,520 MPa (220 ksi), better than 97% of steel grades
Limitations
- Difficult to machine — 18/100, worse than 97% of steel grades
- Limited ductility — 7%, worse than 96% of steel grades
- Difficult to weld — 15/100, worse than 91% of steel grades
- Low fracture toughness — 45 MPa·√m (41 ksi·√in), worse than 90% of steel grades
- Limited service temperature — 230°C (446 °F), worse than 88% of steel grades
FDCrV-OT properties
Typical room-temperature values for FDCrV-OT; 11 are specific to this condition. Other listed values are FDCrV reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
FDCrV-OT has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical13
FDCrV-OT has a yield strength of 1,520 MPa (220 ksi) and a tensile strength of 1,700 MPa (247 ksi) — stronger than 97% of steel grades. Elongation at break is 7% and the elastic modulus is 206 GPa (29.9 Msi).
Thermal6
FDCrV-OT is rated for continuous service to 230°C (446 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
FDCrV-OT conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (14/100), better than 70% of steel grades.
Sustainability4
Producing a kilogram of FDCrV-OT takes about 32 MJ of energy and emits 2.3 kg of CO₂ — more than 70% of steel grades. Typical recycled content is 28%.
Manufacturability7
FDCrV-OT's machinability is poor (18/100, worse than 97% of steel grades); weldability poor (15/100); formability fair (35/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with FDCrV-OT
Is FDCrV easy to machine?
Machine in the annealed condition (≈210 HB, ~55–60 % of 1212); at 45–53 HRC only grinding, EDM or CBN turning is practical.
Can FDCrV be welded?
Effectively unweldable in the tempered spring state — 0.55 % C creates hard martensite and destroys the temper; if unavoidable use preheat 300–350 °C, low-hydrogen filler and immediate PWHT at 480–550 °C.
Can FDCrV be formed, bent or molded?
Cold coil the OT wire at spring index ≥4; always stress-relieve 250–420 °C for 20–30 min after coiling; heavy sections are hot-coiled from annealed stock and then quenched/tempered.
What surface finishes work on FDCrV?
No passive film — protect by zinc or zinc-nickel plating (bake 190–220 °C ≥4 h against hydrogen embrittlement), mechanical zinc, phosphate + oil, or epoxy/powder coat; shot peening is the usual fatigue-improving finish.
FDCrV 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 |
|---|---|---|
| CEN 10270-2 CrV grades | 0.51 – 0.59 | 0.55 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 0.7 – 1.1 | 0.9 |
| Cr | 0.9 – 1.2 | 1.05 |
| Vgrain refinement + temper resistance | 0.1 – 0.25 | 0.15 |
| P | ≤ 0.03 | 0.02 |
| S | ≤ 0.03 | 0.01 |
| Cumax, residual | ≤ 0.12 | 0.05 |
| Fe | balance | — |
FDCrV-OT — frequently asked
What is FDCrV-OT used for?
FDCrV-OT is typically used for automotive valve-type springs, medium-duty compression springs and high-stress mechanical springs. In short: cr-V upgrade over FDC; shock and fatigue duty; 230 °C service limit.
What is the yield strength of FDCrV-OT?
FDCrV-OT has a typical yield strength of 1,520 MPa (220 ksi) and a tensile strength of 1,700 MPa (247 ksi) — stronger than 97% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is FDCrV-OT easy to machine?
Not especially — machinability is rated poor (18/100, worse than 97% of steel grades). Machine in the annealed condition (≈210 HB, ~55–60 % of 1212); at 45–53 HRC only grinding, EDM or CBN turning is practical.
Can FDCrV-OT be welded?
Not readily — weldability is rated poor (15/100). Effectively unweldable in the tempered spring state — 0.55 % C creates hard martensite and destroys the temper; if unavoidable use preheat 300–350 °C, low-hydrogen filler and immediate PWHT at 480–550 °C.
What surface finishes work on FDCrV-OT?
No passive film — protect by zinc or zinc-nickel plating (bake 190–220 °C ≥4 h against hydrogen embrittlement), mechanical zinc, phosphate + oil, or epoxy/powder coat; shot peening is the usual fatigue-improving finish.
Can FDCrV-OT be formed, bent or molded?
Cold coil the OT wire at spring index ≥4; always stress-relieve 250–420 °C for 20–30 min after coiling; heavy sections are hot-coiled from annealed stock and then quenched/tempered.
What is the maximum service temperature of FDCrV-OT?
FDCrV-OT 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 FDCrV-OT and FDCrV-A?
OT is the default condition — standard as-drawn-and-oil-tempered coil for cold-coiled static-duty compression, extension and torsion springs. A: supply state for parts to be machined, hot-coiled or cold-formed and then quenched and tempered by the user. Yield strength is 1,520 MPa in OT versus 450 MPa in A.
Sources
- EN 10270-2 — Steel wire for mechanical springs, Part 2: Oil hardened and tempered spring steel wire — CEN (2011)
- EN 10083-3 — Steels for quenching and tempering, Part 3: Alloy steels (51CrV4) — CEN (2006)
- ASTM A232/A232M — Chromium-Vanadium Alloy Steel Valve-Spring Quality Wire — ASTM (2016)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- EN 13906-1 — Cylindrical helical springs, design and calculation — CEN (2013)
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.