CS · carbon steel
Carbon Steel 12L14 (leaded free-machining)
The fastest-cutting metal on the shop floor and the 10 on our scale. Published index around 170–200% against B1112 = 100%. If a part is a simple turned fitting in volume, this is usually the cheapest way to make it.
Quoting this material
- Typical lead time
- 5–10 working days
- Condition
- Cold drawn, typically
- Achievable finish
- Ra 0.8 µm typical · Ra 0.2 µm best
Machined in-house to your drawing: see the precision CNC machining service and the machine and inspection capability it runs on.
Machinability
Our own 1–10 shop ranking, not a published index: 10 is free-cutting brass C360, 1 is Inconel 718. It ranks how a material behaves on the floor - cycle time, chip control and tool life together. Where a published index exists it is quoted in the note.
The fastest-cutting metal on the shop floor and the 10 on our scale. Published index around 170–200% against B1112 = 100%. If a part is a simple turned fitting in volume, this is usually the cheapest way to make it.
Properties as supplied
| Parameter | Value | Unit |
|---|---|---|
| Tensile strength | 480 | MPa |
| Yield strength | 415 | MPa |
| Elongation | 10 | % |
| Hardness | 163 | HB |
| Thermal conductivity | 51.9 | W/m·K |
| Modulus of elasticity | 200 | GPa |
Hardness, tensile and thermal figures are typical published values for the condition stated. Actual mill certificates govern; send the specification with the drawing and we confirm against the certificate before the material is cut.
Condition
Cold drawn, typically
Heat treatment
Case carburisable, not through-hardenable. The lead is present as a dispersed phase and does not affect the carburising response, but the part cannot be used where a lead-free specification applies.
Achievable surface finish
Ra 0.8 µm
Ra 0.2 µm
Produces the best off-the-tool finish of any steel we run, which is why it is a favourite for visible turned parts.
Tooling and cutting parameters
Cutting speed
- 250–450 m/min (carbide)
Feed
- 0.20–0.45 mm/rev turning · 0.10–0.30 mm/tooth milling
Tooling
- Coated or uncoated carbide; it rewards aggressive feeds
Coolant
- Flood or mist; it is tolerant either way
Starting points for carbide on a rigid setup, not a guarantee. The right numbers depend on the machine, the toolholder and the fixturing - ask and we will say what we would actually run.
Typical applications
- Precision turned fittings and bushings
- Hydraulic and pneumatic adapters
- Connectors and insert bodies
- Shafts for low-load mechanisms
- Volume screw-machine parts
DFM notes for this grade
- Not for welding - the lead and the sulphur make a weld that cracks; a welded assembly needs a different grade
- Restricted in aerospace, nuclear and some medical specifications, and it is not RoHS-relevant but it is lead-containing, which some customers refuse outright
- Corrosion resistance is poor: it machines beautifully and rusts immediately. Plating or black oxide is standard
Questions buyers ask
- Why is leaded steel so much faster to machine?
- The lead sits in the microstructure as a soft, low-friction phase that acts as an internal lubricant and helps the chip break. The result is lower cutting forces, better chip control and a better finish at higher speeds - all three together are worth a large multiple on a volume part.
- Is 12L14 allowed for a customer part in Europe?
- It is not restricted by RoHS, but some customers and specifications ban it by policy, and anything safety-critical will. Ask before quoting - the saving is large enough that it is worth checking rather than assuming.