Steel FDC-CL2
Grade
CL2 = class II
Choose for higher design stress and better set resistance in the same wire size.
Values for the CL2 condition
Other FDC tempers and conditions
FDC is listed in 5 conditions; see the grade overview at FDC.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | For heavy cold forming, heading or parts that will be hardened and tempered after shaping. | 390 | 640 | 22 | 190 HB | — |
Class I | Use when formability and cost matter more than stress level (larger diameters, gentle bends). | 1,250 | 1,480 | 5 | 44 HRC | 9 % IACS |
CDDefault Cold drawn | Standard stocked condition: patented and hard-drawn wire coiled directly into springs. | 1,360 | 1,600 | 4 | 46 HRC | — |
Cold drawn + stress relieved | Post-coiling low-temperature bake: raises elastic limit, relieves coiling stresses and hydrogen, standard for finished springs. | 1,450 | 1,620 | 3.5 | 47 HRC | 9 % IACS |
CL2This page Class II | Choose for higher design stress and better set resistance in the same wire size. | 1,490 | 1,750 | 3 | 49 HRC | 9 % IACS |
What is FDC-CL2?
FDC-CL2 is FDC in the CL2 grade — choose for higher design stress and better set resistance in the same wire size. FDC-CL2 has a yield strength of 1,490 MPa (216 ksi) and a tensile strength of 1,750 MPa (254 ksi) — stronger than 97% of steel grades. Elongation at break is 3% and the elastic modulus is 207 GPa (30 Msi). FDC-CL2 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). CD is the default condition FabDigit quotes; CL2 is available on request or by drawing note.
Advantages
- High strength — 1,490 MPa (216 ksi), better than 97% of steel grades
Limitations
- Limited service temperature — 120°C (248 °F), worse than 100% of steel grades
- Limited ductility — 3%, worse than 99% of steel grades
- Difficult to machine — 20/100, worse than 97% of steel grades
- Difficult to weld — 18/100, worse than 87% of steel grades
FDC-CL2 properties
Typical room-temperature values for FDC-CL2; 22 are specific to this condition. Other listed values are FDC reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
FDC-CL2 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).
Mechanical12
FDC-CL2 has a yield strength of 1,490 MPa (216 ksi) and a tensile strength of 1,750 MPa (254 ksi) — stronger than 97% of steel grades. Elongation at break is 3% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
FDC-CL2 is rated for continuous service to 120°C (248 °F). It conducts heat at 47 W/m·K (27.2 BTU/hr·ft·°F), better than 75% of steel grades. Thermal expansion is 12.5 µm/m·K (6.94 µin/in·°F).
Electrical3
FDC-CL2 conducts electricity at 9 % IACS, better than 71% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of FDC-CL2 takes about 30 MJ of energy and emits 2.3 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 25%.
Manufacturability6
FDC-CL2's machinability is poor (20/100, worse than 97% of steel grades); weldability poor (18/100); formability fair (38/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with FDC-CL2
Is FDC easy to machine?
Rarely machined in the hard-drawn state; grind or use carbide for wire-end operations, or machine after annealing.
Can FDC be welded?
Poor weldability — 0.45–0.85 % C gives brittle martensite in the HAZ and destroys the drawn strength; use mechanical joining or resistance-weld with preheat/post-bake only for non-stressed tabs.
Can FDC be formed, bent or molded?
Coils and bends readily on CNC spring formers; allow for large springback, avoid bend radii below about 2× wire diameter, then bake 230–260 °C for 20–30 min to relieve stresses.
What surface finishes work on FDC?
Supplied oiled or phosphated; zinc/zinc-nickel plating, mechanical galvanizing or powder coating are common — bake within 4 h after electroplating to avoid hydrogen embrittlement; shot peening markedly improves fatigue life.
FDC 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 |
|---|---|---|
| Ccarbon level selected by wire size / tensile class | 0.45 – 0.85 | 0.65 |
| Mn | 0.3 – 1.3 | 0.7 |
| Si | 0.1 – 0.3 | 0.2 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.05 | 0.02 |
| Fe | balance | — |
FDC-CL2 — frequently asked
What is FDC-CL2 used for?
FDC-CL2 is typically used for light mechanical springs, clips and retaining rings and small compression/extension springs. In short: lowest-cost spring wire; hard-drawn, not oil-tempered; 120 °C service ceiling.
What is the yield strength of FDC-CL2?
FDC-CL2 has a typical yield strength of 1,490 MPa (216 ksi) and a tensile strength of 1,750 MPa (254 ksi) — stronger than 97% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is FDC-CL2 easy to machine?
Not especially — machinability is rated poor (20/100, worse than 97% of steel grades). Rarely machined in the hard-drawn state; grind or use carbide for wire-end operations, or machine after annealing.
Can FDC-CL2 be welded?
Not readily — weldability is rated poor (18/100). Poor weldability — 0.45–0.85 % C gives brittle martensite in the HAZ and destroys the drawn strength; use mechanical joining or resistance-weld with preheat/post-bake only for non-stressed tabs.
What surface finishes work on FDC-CL2?
Supplied oiled or phosphated; zinc/zinc-nickel plating, mechanical galvanizing or powder coating are common — bake within 4 h after electroplating to avoid hydrogen embrittlement; shot peening markedly improves fatigue life.
Can FDC-CL2 be formed, bent or molded?
Coils and bends readily on CNC spring formers; allow for large springback, avoid bend radii below about 2× wire diameter, then bake 230–260 °C for 20–30 min to relieve stresses.
What is the maximum service temperature of FDC-CL2?
FDC-CL2 is rated for continuous use to about 120°C (248 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between FDC-CD and FDC-ANN?
CD is the default condition — standard stocked condition: patented and hard-drawn wire coiled directly into springs. ANN: for heavy cold forming, heading or parts that will be hardened and tempered after shaping. Yield strength is 1,360 MPa in CD versus 390 MPa in ANN.
Sources
- ASTM A227/A227M — Steel Wire, Cold-Drawn for Mechanical Springs — ASTM International (2023)
- JIS G 3521 — Hard drawn steel wire — JSA (2020)
- EN 10270-1 — Steel wire for mechanical springs, patented cold drawn unalloyed — CEN (2017)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels and High-Performance Alloys — ASM International (1990)
- SAE HS-795 Spring Design Manual — SAE 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.