Steel TDC
TDC is an oil-tempered plain-carbon spring steel wire of the ASTM A229 class, quenched and tempered in wire form so strength is higher and far more uniform along the coil than cold-drawn FDC.
Reference datasheet — TDC 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.
TDC tempers and conditions
TDC is supplied in 2 conditions, soft to hard.
Compare all 2 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
OQ&T + stress relieved after coiling | Standard post-coiling low-temperature bake to restore elastic limit and stabilise spring free length. | 1,650 | 1,790 | 7 | 51 HRC | 9 % IACS |
OQ&T + stress relieved + shot peened | Choose when cyclic life is the limiting factor: compressive surface stress lifts the fatigue limit by roughly 20–30 %. | 1,650 | 1,810 | 7 | 52 HRC | 9 % IACS |
Supply forms, finishes and certifications
Ways TDC is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
OT-D0.3-1.0 | OQ&T wire, 0.30–1.00 mm diameter | Surface finish |
OT-D1.0-2.0 | OQ&T wire, 1.00–2.00 mm diameter | Surface finish |
OT-D10-17 | OQ&T wire, 10.00–17.00 mm diameter | Surface finish |
OT-D2.0-4.0Default | OQ&T wire, 2.00–4.00 mm diameter | Surface finish |
OT-D4.0-7.0 | OQ&T wire, 4.00–7.00 mm diameter | Surface finish |
OT-D7.0-10.0 | OQ&T wire, 7.00–10.00 mm diameter | Surface finish |
What is TDC?
TDC is an oil-tempered plain-carbon spring steel wire of the ASTM A229 class, quenched and tempered in wire form so strength is higher and far more uniform along the coil than cold-drawn FDC. It is stocked in graded diameter bands from fine to heavy wire, plus stress-relieved and shot-peened conditions, and is the workhorse for cold-coiled compression, extension and torsion springs. Default values are 1600 MPa yield, 1820 MPa tensile and about 52 HRC, with service limited to roughly 130 °C. It is not weldable and has no corrosion resistance; use FDCrV or FDSiCr when fatigue duty or temperature exceeds that range. TDC 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). TDC has a yield strength of 1,580 MPa (229 ksi) and a tensile strength of 1,800 MPa (261 ksi) — stronger than 98% of steel grades. Elongation at break is 7% and the elastic modulus is 206 GPa (29.9 Msi).
What is TDC used for?
- general-purpose compression and extension springs
- mattress springs
- mechanical fastening springs
Advantages
- High strength — 1,580 MPa (229 ksi), better than 98% of steel grades
Limitations
- Limited service temperature — 130°C (266 °F), worse than 100% of steel grades
- Difficult to machine — 12/100, worse than 99% 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
TDC properties
Typical room-temperature values; bars are the position among steel grades.
Physical3
TDC 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).
Mechanical14
TDC has a yield strength of 1,580 MPa (229 ksi) and a tensile strength of 1,800 MPa (261 ksi) — stronger than 98% of steel grades. Elongation at break is 7% and the elastic modulus is 206 GPa (29.9 Msi).
Thermal6
TDC is rated for continuous service to 130°C (266 °F). It conducts heat at 46 W/m·K (26.6 BTU/hr·ft·°F), better than 71% of steel grades. Thermal expansion is 12.5 µm/m·K (6.94 µin/in·°F).
Electrical3
TDC conducts electricity at 9 % IACS, better than 71% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of TDC takes about 30 MJ of energy and emits 2.1 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 22%.
Manufacturability7
TDC's machinability is not recommended (12/100, worse than 99% of steel grades); weldability not recommended (12/100); 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. TDC is highlighted; hover a dot for its name, or open the interactive family chart.
Working with TDC
Is TDC easy to machine?
Supplied fully hardened at ~45–57 HRC — treat as a finished section: cut by abrasive wheel or carbide/CBN parting, grind ends, no conventional turning or drilling.
Can TDC be welded?
Effectively unweldable at 0.65–0.75 %C; any arc or resistance weld destroys the temper and cracks — use hooks, loops or mechanical joints instead.
Can TDC be formed, bent or molded?
Designed for cold coiling straight from the coil on CNC spring machines; keep the spring index above ~4, avoid sharp re-bends of coiled parts, and always bake 230–400 °C for 20–30 min after coiling.
TDC 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 |
|---|---|---|
| Cplain-carbon spring chemistry, no deliberate alloying | 0.6 – 0.75 | 0.68 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 0.6 – 0.9 | 0.75 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Crresidual | ≤ 0.15 | |
| Niresidual | ≤ 0.15 | |
| Curesidual | ≤ 0.12 | |
| Fe | balance |
What surface finishes work on TDC?
No corrosion resistance — phosphate + oil, mechanical zinc, or zinc/zinc-nickel plating with a 190–220 °C hydrogen-relief bake within 4 h; epoxy powder coat for exposed springs.
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
Equivalent designations
Standards and trade names that resolve to Steel TDC in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Similar grades
- A229
How much does TDC cost?
TDC is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
TDC — frequently asked
What is TDC used for?
TDC is typically used for general-purpose compression and extension springs, mattress springs and mechanical fastening springs. In short: oil-tempered general spring wire; more uniform strength than FDC; 130 °C service ceiling.
What is the yield strength of TDC?
TDC has a typical yield strength of 1,580 MPa (229 ksi) and a tensile strength of 1,800 MPa (261 ksi) — stronger than 98% of steel grades. Strength varies by condition: see the 2 listed tempers.
Is TDC easy to machine?
Not especially — machinability is rated not recommended (12/100, worse than 99% of steel grades). Supplied fully hardened at ~45–57 HRC — treat as a finished section: cut by abrasive wheel or carbide/CBN parting, grind ends, no conventional turning or drilling.
Can TDC be welded?
Not readily — weldability is rated not recommended (12/100). Effectively unweldable at 0.65–0.75 %C; any arc or resistance weld destroys the temper and cracks — use hooks, loops or mechanical joints instead.
What surface finishes work on TDC?
No corrosion resistance — phosphate + oil, mechanical zinc, or zinc/zinc-nickel plating with a 190–220 °C hydrogen-relief bake within 4 h; epoxy powder coat for exposed springs.
Can TDC be formed, bent or molded?
Designed for cold coiling straight from the coil on CNC spring machines; keep the spring index above ~4, avoid sharp re-bends of coiled parts, and always bake 230–400 °C for 20–30 min after coiling.
What is the maximum service temperature of TDC?
TDC is rated for continuous use to about 130°C (266 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does TDC cost?
TDC is a budget-cost steel ($), cheaper than about 90% 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)
- ASTM A229/A229M — Steel Wire, Quenched and Tempered for Mechanical Springs — ASTM International (2017)
- JIS G 3560 — Oil tempered wire for mechanical springs — JSA (2019)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (Spring Steels) — ASM International (1990)
- EN 13906-1 — Cylindrical helical springs, design and calculation — CEN (2013)
- Oil tempered spring wire product data (OQ&T carbon grades) — Suzuki Garphyttan / Kobe Steel (2023)
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.