Steel TDCrV OT+SR
Heat-treated state
OT+SR = oT + stress relieved after coiling
Mandatory post-coiling low-temperature bake; raises elastic limit and set resistance with a slight drop in UTS.
Values for the OT+SR condition
Other TDCrV tempers and conditions
TDCrV is listed in 4 conditions; see the grade overview at TDCrV.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed rod/wire | Soft intermediate condition for hot-coiled springs or machined parts that will be quenched and tempered afterwards. | 450 | 700 | 18 | 200 HB | — |
OTDefault Oil hardened and tempered wire, as supplied | Standard as-delivered condition for mid-size coil springs; buy this unless a specific diameter class is needed. | 1,590 | 1,800 | 7 | 51 HRC | — |
OT+SRThis page OT + stress relieved after coiling | Mandatory post-coiling low-temperature bake; raises elastic limit and set resistance with a slight drop in UTS. | 1,650 | 1,780 | 7 | 50 HRC | 8 % IACS |
OT + stress relieved + shot peened spring | Pick for high-cycle dynamic springs: compressive surface stresses lift fatigue strength 20–30 %. | 1,650 | 1,780 | 7 | 51 HRC | 8 % IACS |
What is TDCrV OT+SR?
TDCrV OT+SR is TDCrV heat treated to OT+SR — mandatory post-coiling low-temperature bake; raises elastic limit and set resistance with a slight drop in UTS. TDCrV OT+SR has a yield strength of 1,650 MPa (239 ksi) and a tensile strength of 1,780 MPa (258 ksi) — stronger than 99% of steel grades. Elongation at break is 7% and the elastic modulus is 206 GPa (29.9 Msi). TDCrV OT+SR 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+SR is available on request or by drawing note.
Advantages
- High strength — 1,650 MPa (239 ksi), better than 99% of steel grades
Limitations
- Limited service temperature — 175°C (347 °F), worse than 99% of steel grades
- Difficult to machine — 20/100, worse than 97% of steel grades
- Limited ductility — 7%, worse than 96% of steel grades
- Low fracture toughness — 30 MPa·√m (27.3 ksi·√in), worse than 96% of steel grades
- Difficult to weld — 12/100, worse than 96% of steel grades
TDCrV OT+SR properties
Typical room-temperature values for TDCrV OT+SR; 22 are specific to this condition. Other listed values are TDCrV reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
TDCrV OT+SR 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).
Mechanical13
TDCrV OT+SR has a yield strength of 1,650 MPa (239 ksi) and a tensile strength of 1,780 MPa (258 ksi) — stronger than 99% of steel grades. Elongation at break is 7% and the elastic modulus is 206 GPa (29.9 Msi).
Thermal6
TDCrV OT+SR is rated for continuous service to 175°C (347 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 12.5 µm/m·K (6.94 µin/in·°F).
Electrical3
TDCrV OT+SR conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of TDCrV OT+SR takes about 34 MJ of energy and emits 2.3 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 25%.
Manufacturability7
TDCrV OT+SR's machinability is poor (20/100, worse than 97% of steel grades); weldability not recommended (12/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with TDCrV OT+SR
Is TDCrV easy to machine?
Machine only in the spheroidize-annealed condition; in the 48–54 HRC oil-tempered state use grinding or carbide/CBN tooling for end squaring and tip dressing.
Can TDCrV be welded?
Effectively non-weldable — the high carbon plus Cr-V gives hard, crack-prone HAZ and destroys the temper; use mechanical hooks, loops or crimped end fittings.
Can TDCrV be formed, bent or molded?
Cold coil on CNC formers with generous mandrel ratio (D/d ≥ 4); always bake 250–420 °C for 20–60 min after coiling to relieve residual stress and set the free length.
What surface finishes work on TDCrV?
Shot peen dynamic springs, then phosphate + oil, zinc or zinc-nickel plate (bake ≥190 °C, 4–8 h after plating to avoid hydrogen embrittlement) or epoxy/powder coat for corrosive service.
TDCrV 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 |
|---|---|---|
| CCr-V oil-tempered spring wire base (≈50CrV4/54CrV4; ASTM A231/A232 use 0.48–0.53) | 0.5 – 0.6 | 0.55 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 0.7 – 1.1 | 0.9 |
| Crhardenability and temper resistance | 0.9 – 1.2 | 1.05 |
| Vgrain refinement, carbide strengthening | 0.1 – 0.25 | 0.17 |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Cumax, residual | ≤ 0.12 | — |
| Fe | balance | — |
TDCrV OT+SR — frequently asked
What is TDCrV OT+SR used for?
TDCrV OT+SR is typically used for automotive valve springs, high-fatigue precision springs and heavy-duty compression springs. In short: ready-tempered spring wire; cr-V valve spring quality; high fatigue strength.
What is the yield strength of TDCrV OT+SR?
TDCrV OT+SR has a typical yield strength of 1,650 MPa (239 ksi) and a tensile strength of 1,780 MPa (258 ksi) — stronger than 99% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is TDCrV OT+SR easy to machine?
Not especially — machinability is rated poor (20/100, worse than 97% of steel grades). Machine only in the spheroidize-annealed condition; in the 48–54 HRC oil-tempered state use grinding or carbide/CBN tooling for end squaring and tip dressing.
Can TDCrV OT+SR be welded?
Not readily — weldability is rated not recommended (12/100). Effectively non-weldable — the high carbon plus Cr-V gives hard, crack-prone HAZ and destroys the temper; use mechanical hooks, loops or crimped end fittings.
What surface finishes work on TDCrV OT+SR?
Shot peen dynamic springs, then phosphate + oil, zinc or zinc-nickel plate (bake ≥190 °C, 4–8 h after plating to avoid hydrogen embrittlement) or epoxy/powder coat for corrosive service.
Can TDCrV OT+SR be formed, bent or molded?
Cold coil on CNC formers with generous mandrel ratio (D/d ≥ 4); always bake 250–420 °C for 20–60 min after coiling to relieve residual stress and set the free length.
What is the maximum service temperature of TDCrV OT+SR?
TDCrV OT+SR is rated for continuous use to about 175°C (347 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between TDCrV-OT and TDCrV-SA?
OT is the default condition — standard as-delivered condition for mid-size coil springs; buy this unless a specific diameter class is needed. SA: soft intermediate condition for hot-coiled springs or machined parts that will be quenched and tempered afterwards. Yield strength is 1,590 MPa in OT versus 450 MPa in SA.
Sources
- EN 10270-2 — Steel wire for mechanical springs, Part 2: Oil hardened and tempered spring steel wire — CEN (2011)
- ASTM A232/A232M — Chromium-Vanadium Alloy Steel Valve Spring Quality Wire — ASTM (2019)
- ASTM A231/A231M — Chromium-Vanadium Alloy Steel Spring Wire — ASTM (2019)
- EN 13906-1 — Cylindrical helical springs, design and calculation — CEN (2013)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
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.