CS · carbon steel
Carbon Steel 1215 (rephosphorised and resulphurised)
The other free-machining steel. Very close to 12L14 in behaviour, lead-free but higher in sulphur and phosphorus - a strong option where leaded steel is not permitted.
Quoting this material
- Typical lead time
- 5–10 working days
- Condition
- Cold drawn
- Achievable finish
- Ra 0.8 µm typical · Ra 0.4 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 other free-machining steel. Very close to 12L14 in behaviour, lead-free but higher in sulphur and phosphorus - a strong option where leaded steel is not permitted.
Properties as supplied
| Parameter | Value | Unit |
|---|---|---|
| Tensile strength | 540 | MPa |
| Yield strength | 415 | MPa |
| Elongation | 7 | % |
| Hardness | 170 | 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
Heat treatment
Case carburisable, not through-hardenable. Rephosphorised grades are also notch sensitive, so a sharp internal corner is more of a risk than on a plain carbon steel.
Achievable surface finish
Ra 0.8 µm
Ra 0.4 µm
Excellent turned finish, close to 12L14; slightly less bright due to the higher sulphur.
Tooling and cutting parameters
Cutting speed
- 250–400 m/min (carbide)
Feed
- 0.15–0.40 mm/rev turning · 0.10–0.25 mm/tooth milling
Tooling
- Coated carbide
Coolant
- Flood or mist
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
- Volume turned fasteners and studs
- Fittings and couplings
- Bushing and spacer stock
- Screw-machine shafts
- Leaded-free free-machining parts
DFM notes for this grade
- Lower ductility than 1018: a 7% elongation means it does not like being bent after machining
- Not welded: the sulphur content makes the weld porous and crack-prone
- It is the lead-free answer but it is still a free-machining grade - where a specification bans free-machining additives entirely, neither 1215 nor 12L14 is acceptable
Questions buyers ask
- 1215 or 12L14 if the specification bans lead?
- 1215, and it costs little more to machine. The compromise is ductility - 1215 is more notch sensitive and will crack at a sharp corner that 12L14 shrugs off, so any part with a stress concentration in a free-machining steel deserves a second look at the corner radius.
- Can free-machining steel be used for a safety-critical part?
- It is usually excluded by policy. The inclusions that make these steels fast to machine are also crack initiators under fatigue, which is why aerospace and nuclear specifications name the alloy, the cleanliness class and often the melting practice. Do not substitute.