CS · carbon steel
Carbon Steel 1137 (resulphurised medium carbon)
Medium carbon with sulphur added: it machines nearly as well as a free-cutting grade and still hardens. The compromise between 1045 and 12L14.
Quoting this material
- Typical lead time
- 5–10 working days
- Condition
- Cold drawn, or hot rolled and normalised
- Achievable finish
- Ra 1.6 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.
Medium carbon with sulphur added: it machines nearly as well as a free-cutting grade and still hardens. The compromise between 1045 and 12L14.
Properties as supplied
| Parameter | Value | Unit |
|---|---|---|
| Tensile strength | 620 | MPa |
| Yield strength | 420 | MPa |
| Elongation | 12 | % |
| Hardness | 187 | HB |
| Thermal conductivity | 49.8 | W/m·K |
| Modulus of elasticity | 205 | 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, or hot rolled and normalised
Heat treatment
Through-hardenable and commonly supplied pre-hardened around 32 HRC for studs and bolts. The sulphur reduces ductility slightly but does not prevent hardening.
Achievable surface finish
Ra 1.6 µm
Ra 0.4 µm
Good turned finish; no bright-finish capability but very serviceable.
Tooling and cutting parameters
Cutting speed
- 180–300 m/min (carbide)
Feed
- 0.15–0.35 mm/rev turning · 0.08–0.20 mm/tooth milling
Tooling
- Coated carbide
Coolant
- Flood
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
- Studs and threaded rods
- Bolts and fasteners (machined)
- U-bolts and clamps
- Coupling and sleeve parts
- Pre-hardened pins
DFM notes for this grade
- A good answer for a threaded part that has to harden: far easier to machine than 1045 at the same strength class
- Still not a welding steel - the sulphur carries the same crack risk as in 1215, so welded assemblies should use 1018 or 1020
- Where a fastener specification bans resulphurised steel, the fallback is 4140 or 1045 and the cycle time rises accordingly
Questions buyers ask
- Where does 1137 sit between 12L14 and 1045?
- In the middle, and that is genuinely useful. It is roughly 40% faster to machine than 1045 while still hardening to a useful strength - for a stud that has to be threaded and heat treated, that combination is worth more than either extreme.
- Does the sulphur reduce fatigue life?
- Yes, measurably, which is why it is not used for a part that sees high cyclic stress. Fasteners in static tension are fine; a rotating shaft or a part under vibration loading belongs in a cleaner steel.